FIELD OF THE INVENTION
The present invention relates to Roll Bite Lubrication System for hot rolling mills.
More particularly, the present invention is directed to a pilot roll bite lubrication
system developed for application of lubrication involving preparation and application
of rolling oil dispersion at the roll bite of hot rolling mills. The system is of mobile
type and can be applied at the laboratory mill scale as well as at the industrial hot
rolling mill. Importantly, the operating parameters like flow rate, pressure, and
dispersion concentration of lubricant can be varied in a specified range by the
lubrication system. The Roll Bite Lubrication system according to the present
invention adapted for application of lubrication in hot rolling mills incorporates a
built-in automation system for operating it automatically matching with the biting
condition of the mill. Advantageously also, the system can be used for comparative
evaluation of the benefits of lubrication in the mill using different types of rolling oils
under laboratory and industrial conditions. The system is adapted to be customized
to suit full size industrial lubrication system according to the operating conditions of
any given hot rolling mill. Significant reduction in roll force, power and roll wear have
been achieved with the application of lubrication using Pilot Roll Bite Lubrication
system in hot rolling mills ensuring the prospect of wide industrial application.
BACKGROUND OF THE INVENTION
It is well known in any steel mill that roll bite lubrication (RBL) works on principle of
creating a thin molecular boundary layer of lubricant between the mating surfaces of
workpiece and work rolls. The lubricant film reduces the contact area of interaction
and thus decreases the levels of friction and wear rate at the roll bite. The benefit
can further be converted to improvements in production of mill, life of rolls and
quality of the rolled products. The lubricating oil is normally applied in the form of
oil-in-water emulsion or dispersion. RBL has been considered compulsory in cold
rolling mills as their integral part. In hot rolling mills, application of RBL is relatively
new and many such mills are working even without lubrication. Type of lubricating oil
and method of its application are quite different in cold and hot rolling mills,
particularly due to difference in level of workpiece temperature, load conditions and
material characteristics.
Performances of hot rolling mills are directly dependent on friction and wear
conditions at the roll bite of work rolls. With reduction in friction, it is possible to
reduce roll force and power requirements of the mill, which is helpful in rolling critical
grades and sizes of material. By reducing wear rate of rolls, it is possible to increase
campaign size of rolling for enhanced production level beside reduction in specific
consumption of rolls. Both the friction and wear can be reduced by introduction of
lubrication at the roll bite.
It has been investigated that success of RBL system in any hot rolling mill depends
on three important aspects:
(a) Suitable chemistry of hot rolling oil,
(b) Properly designed oil application system (RBL system), and
(c) Optimised operating conditions (stabilisation of RBL system).
For identifying suitable chemistry of the oil, it is required to try out various
alternative formulations and compare their performances in laboratory on suitable
test rigs / equipments. It is normally a practice to evaluate physico-chemical
properties of the oil (like saponification value, acid value, viscosity, flash point, etc.)
however these are not directly and conclusively related to the actual performance of
the oil in a given mill. Performance data generated at some of the tribological rigs,
like Amsler Wear Tester, LFW-1 Friction Tester, Pin-on-V Block Tester, etc., are also
not representative as these rigs do not simulate the rolling or deformation conditions
of hot mills. In laboratory, the rolling conditions are best simulated at experimental
rolling mill, generally having single stand reversing/non-reversing configuration.
Unfortunately, this type of mills is normally not equipped with system for application
of the hot rolling oil. It is therefore required to develop setup for preparation of oil-
in-water dispersion, spraying it on the rolls and controlling flow conditions.
After selecting the most favourable oil composition in laboratory, it is required to
evaluate its performance at the industrial mill. The industrial mill should also have a
properly designed RBL system. The important design parameters may include flow
rate and pressure of oil, flow rate and pressure of water, mixing condition of oil and
water, spray condition of dispersion and automation scheme for control of flow
parameters. For achieving the best possible benefits from RBL, the system needs to
be stabilised for optimising the operating conditions.
With the above objective, a Pilot RBL system was initially developed for a single
stand 400 mm reversing Experimental Rolling Mill, adapted to be used both in hot
rolling (2-Hi) and cold rolling (4-Hi) modes. The mill was initially not equipped for
applying lubrication in hot rolling mode. It was only having a recirculation type
emulsion system for using in cold rolling mode. In this system, cold rolling oil and
water were mixed in a tank using motorized agitator and immersion heater. The
emulsion so prepared was pumped (using centrifugal pump) to a header for spraying
it over the rolls. The sprayed emulsion was recollected and returned to the same
emulsion tank for further cycles of operation.
It was not possible to use the existing emulsion system of cold rolling mode in hot
rolling mode because of the following reasons:
(a) Hot rolling oil is quite different from the cold rolling oil in terms of its
emulsion stability. The hot rolling oil is highly unstable as film is to be
formed in quicker time. If the oil and water are mixed in the tank, which is
placed far away from the stand, then oil separates out from the water in
pipeline itself. For hot rolling it is required to mix the oil with water at very
close to spray point.
(b) While cold rolling uses recirculation type system, the hot rolling requires a
total loss system as the oil gets burnt with the heat of workpiece.
(c) Cold rolling uses same emulsion for cooling as well as lubrication purpose.
Volume of roll cooling water is much higher than that required for making
hot roiling dispersion. Mixing even less than 1% oil consumes lots of oil. It is
therefore required to have separate cooling of lubrication systems in hot
rolling.
(d) Since flow rate of hot rolling oil is very less but precise, the use of
centrifugal pump is not feasible. It requires a reciprocating type metering or
dosing pump for supplying metered quantity of the oil.
(e) In cold rolling, emulsion is sprayed continuously from one end to other end
of the coil. In hot rolling, two ends are to be rolled in dry condition (without
lubrication) to avoid the problem of skidding during feeding of materials in
the bite. It is therefore required to operate the oil pump intermittently using
an automation system.
(f) In cold rolling the desired emulsion concentration is maintained by adding
suitable oil quantity of oil in emulsion tank. In hot rolling, since dispersion is
not prepared in tank but in a small mixer, it is required to have variable
discharge from the oil pump.
It is thus apparent based on the foregoing discussions that there has been a need in
the art to develop a roll bite lubrication (RBL) system which can be used with
experimental as well as industrial hot rolling mills to study various aspects of
lubrication at roll bite while taking care of the basic operational requirements in hot
rolling mills as detailed above.
An independent Pilot RBL system has therefore been developed by way of the
present invention to prepare hot rolling oil-in-water dispersion and spray them over
the top and bottom work or backup rolls of the experimental or industrial mill to
evaluate the favourable impact of such roll bite lubrication in hot rolling mill in terms
of reduction in roll force, power and roll wear and resultant improvement in
production of mill, life of rolls and quality of the rolled products, which was later
applied for operation on industrial scale with satisfactory results.
OBJECTS OF THE INVENTION
The basic object of the present invention is thus directed to providing a roll bite
lubrication system for hot rolling mill which would be able to prepare hot rolling oil-
in-water dispersion and spray them over the rolls of the experimental as well as
industrial mill with provision for required stability of emulsion and means for
optimizing the operating conditions for desired performance.
Another object of the present invention is directed to providing a roll bite lubrication
system for hot rolling mill which would ensure desired flow rate and pressure of oil,
flow rate and pressure of water, mixing condition of oil and water, spray condition of
dispersion and automation scheme for control of flow parameters.
A still further object of the present invention is directed to providing a roll bite
lubrication system for hot rolling mill wherein oil is mixed with water very close to
spray point.
A still further object of the present invention is directed to providing a roll bite
lubrication system for hot rolling mill wherein the system is designed for total loss
type lubrication system.
Yet another object of the present invention is directed to providing a roll bite
lubrication system for hot rolling mill wherein metered quantity of the hot rolling
lubricating oil is supplied to maintain desired proportion of oil and water involving a
reciprocating type metering or dosing pump.
A further object of the present invention is directed to providing a roll bite lubrication
system for hot rolling mill wherein to ensure that two ends of coil are rolled in dry
condition (without lubrication) to avoid the problem of skidding during feeding of
materials in the bite, the oil pump is operated intermittently using on / off switching
by an automation system.
A still further object of the present invention is directed to providing a roll bite
lubrication system for hot rolling mill wherein automation involving PLC is
implemented by sensing and processing a combination of signals from load cell of the
mill and hot metal detector (HMD) placed at entry of the mill.
A still further object of the present invention is directed to providing a roll bite
lubrication system for hot rolling mill wherein spray of the dispersion over the rolls is
controlled by segmented headers with nozzles reducing wastage of oil by adjusting
flow of dispersion through segments based on width of coils being processed.
A still further object of the present invention is directed to providing a roll bite
lubrication system for hot rolling mill wherein the headers are provided with
swiveling arrangement for changing the impinging angle of oil-water dispersion as
per need.
A still further object of the present invention is directed to providing a roll bite
lubrication system for hot rolling mill wherein all major components except mixer
and headers are installed on a movable trolley to give the system mobility so that it
can be shifted from one mill to the other or alternatively built to be stationary based
on its end use/application.
SUMMARY OF THE INVENTION
The basic aspect of the present invention is directed to a roll bite lubrication system
for preparation and application of rolling oil dispersion on rolls of hot rolling mills
comprising:
means for mixing oil and water at high pressure in a mixer;
means for variable level of lubrication at the roll bite involving controllable varying
concentration and pressure of dispersion ;and
means adapted for effective spraying over the work or backup roll such as to favour
total loss arrangement whereby almost all the oil sprayed over the rolls is burnt and
is free of any recirculation of the dispersion.
A further aspect of the present invention is directed to a roll bite lubrication system
wherein said means for varying concentration comprises means for varying flow
rates of oil and water and said means for varying pressure of dispersion comprises
valve means and return pipelines from water pump to a tank and said means for
effective spraying comprises means adapted to vary the place and angle of
impingement of spray over the roll surface for effective lubrication.
A still further aspect of the present invention is directed to a roll bite lubrication
system comprising means to control (i) oil flow rate 0 to 0.80 l/min (ii) water flow
rate up to 80 l/min (iii) concentration of dispersion of the order of 0-1.0% (iv)
pressure of dispersion up to 7 bar (v) On/off timing of oil spray and (vi) angle of
spray with rolling direction.
A still further aspect of the present invention is directed to a roll bite lubrication
system wherein for precise control of the oil flow rate involve reciprocating type
duplex proportion pump coupled with a variable frequency drive arrangement for
varying its stroke speed as per requirement of flow rate, with separate cylinder for
supplying lubricant to top and bottom rolls, for maintaining differential flow rate of oil
at the two rolls.
A still further aspect of the present invention is directed to a roll bite lubrication
system wherein flow condition of the water is controlled involving centrifugal pump,
filter and suitable valve arrangements such that water is kept running ail along the
mill operation to keep the pipeline primed all the time.
Yet another aspect of the present invention is directed to a roll bite lubrication
system wherein said mixer is a tube type mixer for mixing of the oil-in-water
achieved by feeding oil and water at high pressure through two different ports at one
end of the tube whereby the oil forms droplets due to shearing force applied by spiral
inner construction (shearing blade) of the tube and the dispersion of oil droplets in
the water phase comes out from the other end of the tube.
A further aspect of the present invention is directed to a roll bite lubrication system
wherein in the said mixer rate of shearing of the oil and resulting oil droplet size and
dispersion stability can be varied involving means adapted for varying the pressure,
tube size and angle of the shearing blade.
A still further aspect of the present invention is directed to a roll bite lubrication
system comprising means for controlled spray of the dispersion over the rolls
preferably through segmented headers with flat jet type nozzles with spacing of
nozzles selected such that there is good amount of overlaps among the adjacent
sprays.
A still further aspect of the present invention is directed to a roll bite lubrication
system wherein said segmented headers are adapted to reduce wastage of oil by
stopping flow of dispersion through the end segments while processing of narrower
coils and selecting flow through the end segments activated using solenoid valve
during processing of wider coils.
A further aspect of the present invention is directed to a roll bite lubrication system
wherein header ends are provided with swivel arrangement for changing
impingement angle over the roll surface.
Yet another aspect of the present invention is directed to a roll bite lubrication
system comprising means adapted to thread the material in the mill under dry
lubrication condition, to avoid skidding of rolls during threading, automatic switching
on/off of the oil pump comprising of a programmable logic controller (PLC), based on
a combination of signals from load cell of the mill and hot metal detector (HMD)
placed at entry of the mill whereby the pump gets on only when the PLC receives
signals from both the sources including involving a time lag set for delayed start of
the pump after threading of the material in the mill stand and the pump gets off as
soon as signal from HMD is unavailable.
A further aspect of the present invention is directed to a roll bite lubrication system
comprising means for recording/monitor the operating parameters such as Flow rate
and pressure of oil, Flow rate and pressure of water, Pressure of dispersion, Level of
oil and water in their respective tanks, and Energy consumption.
A still further aspect of the present invention is directed to a roll bite lubrication
system comprising programmable logic controller provided with a human machine
interface (HMI) for setting the test parameters as well as for viewing the report
whereby it is possible to automatically fill oil and water in respective tanks whenever
level of fluid in the tank goes below a set value.
A further aspect of the present invention is directed to a roll bite lubrication system
which is portable wherein all major components except mixer and headers are
installed on a movable trolley to give the system mobility so that it can be shifted
from one mill to the other or alternatively built to be stationary based on its end
use/application.
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: illustrates the Flow diagram of pilot roll bite lubrication system according to
the present invention showing the various components used in the system wherein
components located at block 'A' are installed on trolley while those located at block
*B' are installed at mill stand.
Figure 2: illustrates with the help of bar chart the effect of RBL on roll force at the
first finishing stand of a hot strip mill.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING FIGURES
The present invention is directed to providing a pilot roll bite lubrication system for
hot rolling mills adapted to prepare the required oil-in-water dispersion for spray
over rolls and automation system to inject the lubricant maintaining the optimized
process parameters including desired flow rate and pressure of oil, flow rate and
pressure of water, mixing condition of oil and water, spray condition of dispersion
and automation scheme for control of flow parameters for favourable plant operation
and desired results in respect of reduced roll force, power and roll wear and resultant
improvement in production of mill, life of rolls and quality of the rolled products.
Reference is first invited to the accompanying Figure 1 that illustrates schematically
the components deployed in the RBL system for hot rolling mill according to the
present invention with the help of a flow chart to show the functional
interdependence of the components, one in relation to the others in the system.
It can be identified in the Figure 1, that the system comprises an oil feeding line
and a water feeding line. An oil tank store hot roiling oil for supply to oil pump and a
water tank store water for supply to water pump. Level sensors (not shown in figure)
are provided with the tanks for measurement and display of level of oil and water in
their respective tanks and automatically/manually refilling the tanks from their feed
lines. Filter/strainer is provided for cleaning of water/oil supplied from the respective
tanks. A metering oil pump-motor set is provided to supply oil separately to mixers
for top and bottom rolls at specified flow rate and pressure. A variable frequency
drive (VFD) is provided to drive metering pump to automatically control supply of oil
flow rate at the specified flow rate. A centrifugal water pump-motor set supply water
separately to mixers for top and bottom rolls at specified flow rate and pressure.
Flow meters are provided to automatically measure the flow rate of oil and water
separately in each flow line. A calibration cylinder in the oil feeding line ensures
manual measurement of flow rate of oil for cross checking or calibrating flow
measurement with flow meter. Separate pressure transmitters are provided to
measure supply pressure of oil, water and dispersion in each flow line. Manual
control of oil and water flow is performed using gate/globe valves and automatic
control of fluid flow is achieved by using solenoid valves. A tube mixer ensures
mixing of oil and water for dispersion at specified flow rate and pressure. Spraying of
dispersion over work/backup rolls at specified flow rate and pressure is accomplished
through the segmented spray headers with nozzles. Programmable controller (PLC)
with human machine interface (HMI) is provided in the system for automatically
switching on and off the oil pump at specified logic depending upon biting condition
of the material in mill. An Electrical panel is provided for housing power system, PLC,
HMI, VFD, energy meter, relays, switches, circuit breaker, level monitor, flow meter
monitor, etc. Energy meter enable measurement of energy consumed in rolling with
and without lubrication. All major components as detailed above except mixers and
headers are housed on movable trolley to give the system mobility.
The Pilot RBL system as described above has the following operational features:
(a) Functional: The Pilot RBL system has been developed for preparation and
application of rolling oil dispersion in the hot rolling mills. In this system, dispersion
of oil-in-water is prepared by mixing them at high pressure in a mixer close to the
mill stand and is sprayed over the work or backup rolls. It is designed as total loss
system where almost all the oil sprayed over rolls is burnt with the heat of material
being rolled. There is no recirculation of dispersion in the system.
(b) Versatility: The system has been designed to provide flexible operating
conditions and it can be used at different type of hot rolling mills (flat and long
product mills). Level of lubrication at the roll bite can be varied by varying
concentration and pressure of dispersion. The former can be varied by varying flow
rates of oil and water. The latter can be varied with the help of mechanical valves
and return pipelines from water pump to the tank. Place and angle of impingement
of spray over the roll surface can also be changed to vary the lubrication
effectiveness.
(c) Variable parameters: The system can be used to carry out studies at
experimental / industrial hot rolling mills with the following variable parameters:
• Oil flow rate from 0 to 0.80 l/min
• Water flow rate up to 80 l/min
• Concentration of dispersion of the order of 0-1.0%
• Pressure of dispersion up to 7 bar
• On/off timing of oil spray
• Angle of spray with rolling direction
(d) Flow control: Precise control of the oil flow rate is achieved using reciprocating
type duplex proportion pump. It is coupled with a variable frequency drive
arrangement for varying its stroke speed as per requirement of flow rate. Separate
cylinder is used for supplying lubricant to top and bottom rolls, which is useful in
maintaining differential flow rate of oil at the two rolls, if so required. Flow condition
of the water is controlled using centrifugal pump, filter and suitable valve
arrangements. Water is kept running all along the mill operation to keep the pipeline
primed all the time.
(e) On/Off switching Control: The Pilot RBL system is capable to thread the
material in the mill under dry lubrication condition, which is required to avoid
skidding of rolls during threading. It is achieved through automatic switching on/off
of the oil pump using a programmable logic controller (PLC), which uses a
combination of signals from load cell of the mill and hot metal detector (HMD) placed
at entry of the mill. The pump gets on only when the PLC receives signals from both
the sources. A time lag can also be set for delayed start of the pump after threading
of the material in the mill stand. The pump gets off as soon as signal from HMD is
unavailable.
(f) Mixing & spray: Mixing of the oil-in-water is achieved using a tube type mixer
where oil and water are fed at high pressure through two different ports at one end
of the tube. The oil forms droplets due to shearing force applied by spiral inner
construction (shearing blade) of the tube. The dispersion of oil droplets in the water
phase comes out from the other end of the tube. Rate of shearing of the oil and
resulting oil droplet size and dispersion stability can be varied by varying the
pressure, tube size and angle of the shearing blade.
Spray of the dispersion over the rolls is achieved through segmented headers with
flat jet type nozzles. The segment design of header helps in reducing wastage of oil
by stopping flow of dispersion through the end segments while processing of
narrower coils. Selection of flow through the end segments is activated using
solenoid valve during processing of wider coils. The spacing of nozzles is selected
such that there is good amount of overlaps among the adjacent sprays. Header ends
are provided with swivel arrangement for changing impingement angle over the roll
surface.
(g) Instrumentation: The Pilot RBL system is designed with suitable
instrumentation system for recording/monitoring the following parameters:
• Flow rate and pressure of oil
• Flow rate and pressure of water
• Pressure of dispersion
• Level of oil and water in their respective tanks
• Energy consumption
PLC of the Pilot RBL system has been provided with a human machine interface
(HMI) for setting the test parameters as well as for viewing the report. It is possible
to automatically fill oil and water in their tanks whenever level of fluid in the tank
goes below a set value.
The performance of the above described Pilot RBL system according to the invention
has been evaluated by way of following examples:
Example I:
The above described Pilot RBL system has been installed at the experimental rolling
mill and testing of the system has been carried out using a semi-synthetic rolling oil
and evaluating the performance of the system with respect to following functions:
(a) Automatic switching on and off the oil pump was checked using load cell signal
from the mill and pyrometer signal taken from the furnace. For this hot rolling of
steel sample was carried out in the mill. With the availability of pyrometer signal, the
pump became ready. As soon as the steel was fed in the bite, a load cell signal was
available to the PLC, which switched on the oil pump. Oil pump was switched off by
disconnecting the signal from pyrometer. This confirmed that the system was
functioning automatically.
(b) Control of flow rate of oil was checked by setting the VFD of oil pump at different
frequency from 10-50 Hz and measuring the oil flow rate using calibration cylinder. It
was confirmed that flow rate of oil was controllable to the specified level of 0.80 Ipm
by using the VFD.
(c) Achieving the specified flow rate and pressure of the water pump was checked by
operating the pump with different level of return flow. Maximum flow rate of 80 Ipm
at 5 bar pressure was achieved. It was possible to achieve water pressure of 3-7 bar
at spray header.
(d) Effect of RBL on performance of the experimental mill has been checked by hot
rolling of 5 mild steel plate samples with lubrication and 5 samples without
lubrication. The initial size of the samples taken was 25 mm thick x 100 mm wide x
350 mm long which were heated and soaked in reheating furnaces for 30 minutes at
1000 °C. These samples were rolled to finished thickness of 6 mm in 3 passes. Roll
force in each pass was measured using load cell and compared in both the cases, i.e.
with and without lubrication. The effect of RBL on roll force at experimental rolling
mill using pilot RBL system based on data relating to above sample trials are shown
in the following Table 1.

From the above experiments, it is concluded that roll force could be reduced by 5-
20% in different passes by application of lubrication using pilot RBL system.
Example II:
After satisfactory performance of the Pilot RBL system could be established in the
experimental mill, the same system was transferred to an industrial hot strip mill of
an integrated steel plant, which did not have any system for application of RBL.
The Pilot RBL system has been installed in the mill to apply lubrication at the bite of
the first finishing stand (Fl) having details of the stand as given below:
-Work roll diameter & barrel length: 760mm (new) / 710mm (scrap) x 1730mm
-Backup roll diameter & barrel length: 1310mm (new) / 1180mm (scrap) x
1700mm
-Work roll material: Hi-Cr Iron
-Backup roll material: Alloy forged steel
-Maximum (limiting) roll force: 28 MN
-Thickness of transfer bar: 25-30 mm
-Pass reduction: 30-35%
-Temperature of material: ~ 1000 °C
-Application point of RBL: On back up rolls at exit side
The same rolling oil, which was used at the experimental rolling mill, was used for
lubrication purpose at the hot strip mill. Oil pump of the system was operated using
signals of strip-in-mill (load cell) of the Fl stand and HMD placed at entry to the Fl
stand. Oil flow rate was slowly increased to maximum about 200 ml/min. However,
due to tendency of skidding of rolls at higher flow rate, it was stabilised at 140-150
ml/min.
With the application of lubrication using Pilot RBL system according to the present
invention at the Fl stand, the following industrial benefits were demonstrated to
finally validate the design of the Pilot RBL system:
-Roll force reduced by 7-10% during processing various grades and sizes of hot
rolled coils as illustrated in accompanying Figure 2.
*
-Energy consumption also reduced by 8-10% with the use of lubrication.
-Wear of work rolls in various campaigns reduced by 40-60% depending upon
campaign size.
-The above benefits were achieved at a low specific oil consumption of 10-12 ml/t
of rolled steel.
It is thus possible by way of the present invention to developing a pilot roll bite
lubrication system for hot rolling mills adapted to preparation and application of oil-in
water dispersion for spray on rolls with automated operation and optimization of
process parameters ensuring reduction in friction to reduce roll force and power
requirements of the mill, reducing wear rate of rolls to increase campaign size of
rolling for enhanced production level besides reduction is specific consumption of
rolls.
We Claim:
1. A roll bite lubrication system for preparation and application of rolling oil
dispersion on rolls of hot rolling mills comprising:
means for mixing oil and water at high pressure in a mixer;
means for variable level of lubrication at the roll bite involving controllable
varying concentration and pressure of dispersion ;and
means adapted for effective spraying over the work or backup roll such as to
favour total loss arrangement whereby almost all the oil sprayed over the rolls is
burnt and is free of any recirculation of the dispersion.
2. A roll bite lubrication system as claimed in claim 1 wherein said means for
varying concentration comprises means for varying flow rates of oil and water
and said means for varying pressure of dispersion comprises valve means and
return pipelines from water pump to a tank and said means for effective spraying
comprises means adapted to vary the place and angle of impingement of spray
over the roll surface for effective lubrication.
3. A roll bite lubrication system as claimed in anyone of claims 1 or 2 comprising
means to control (i) oil flow rate from 0 to 0-80 l/mim (ii) water flow rate up to
80 l/min (iii) concentration of dispersion of the order of 0-1.0% (iv) pressure of
dispersion up to 7 bar (v) On/off timing of oil spray and (vi) angle of spray with
rolling direction.
4. A roll bite lubrication system as claimed in anyone of claims 1 to 3 wherein for
precise control of the oil flow rate involve reciprocating type duplex proportion
pump coupled with a variable frequency drive arrangement for varying its stroke
speed as per requirement of flow rate, with separate cylinder for supplying
lubricant to top and bottom rolls, for maintaining differential flow rate of oil at the
two rolls.
5. A roll bite lubrication system as claimed in anyone of claims 1 to 4 wherein flow
condition of the water is controlled involving centrifugal pump, filter and suitable
valve arrangements such that Water is kept running all along the mill operation
to keep the pipeline primed all the time.
6. A roll bite lubrication system as claimed in anyone of claims 1 to 5 wherein said
mixer is a tube type mixer for mixing of the oil-in-water achieved by feeding oil
and water at high pressure through two different ports at one end of the tube
whereby the oii forms droplets due to shearing force applied by spiral inner
construction (shearing blade) of the tube and the dispersion of oil droplets in the
water phase comes out from the other end of the tube.
7. A roll bite lubrication system as claimed in anyone of claims 1 to 6, wherein in
said mixer rate of shearing of the oil and resulting oil droplet size and dispersion
stability can be varied involving means adapted for varying the pressure, tube
size and angle of the shearing blade.
8. A roll bite lubrication system as claimed in anyone of claims 1 to 7 comprising
means for controlled spray of the dispersion over the rolls preferably through
segmented headers with flat jet type nozzles with spacing of nozzles selected
such that there is good amount of overlaps among the adjacent sprays.
9. A roll bite lubrication system as claimed in anyone of claims 1 to 8 wherein said
segmented headers are adapted to reduce wastage of oil by stopping flow of
dispersion through the end segments while processing of narrower coils and
selecting flow through the end segments activated using solenoid valve during
processing of wider coils.
10. A roll bite lubrication system as claimed in anyone of claims 1 to 9 wherein
header ends are provided with swivel arrangement for changing impingement
angle over the roll surface.
11. A roll bite lubrication system as claimed in anyone of claims 1 to 10 comprising
means adapted to thread the material in the mill under dry lubrication condition,
to avoid skidding of rolls during threading, automatic switching on/off of the oil
pump comprising of a programmable logic controller (PLC), based on a
combination of signals from load cell of the mill and hot metal detector (HMD)
placed at entry of the mill whereby the pump gets on only when the PLC receives
signals from both the sources including involving a time lag set for delayed start
of the pump after threading of the material in the mill stand and the pump gets
off as soon as signal from HMD is unavailable.
12. A roll bite lubrication system as claimed in anyone of claims 1 to 11 comprising
means for recording/monitor the operating parameters such as Flow rate and
pressure of oil, Flow rate and pressure of water, Pressure of dispersion, Level of
oil and water in their respective tanks, and Energy consumption.
13. A roll bite lubrication system as claimed in anyone of claims 1 to 12 comprising
programmable logic controller provided with a human machine interface (HMI)
for setting the test parameters as well as for viewing the report whereby it is
possible to automatically fill oil and water in respective tanks whenever level of
fluid in the tank goes below a set value.
14. A roll bite lubrication system as claimed in anyone of claims 1 to 13 which is
portable wherein all major components except mixer and headers are installed on
a movable trolley to give the system mobility so that it can be shifted from one
mill to the other or alternatively built to be stationary based on its end
use/application.

ABSTRACT

The present invention relates to a Roll Bite Lubrication (RBL) System for hot rolling
mills and in particular to a pilot roll bite lubrication system developed for application
of lubrication involving preparation and application of rolling oil dispersion at the roll
bite of hot rolling mills. The system is of mobile type and can be applied at the
laboratory scale mill as well as at the industrial hot rolling mill. The operating
parameters like flow rate, pressure, and dispersion concentration of lubricant can be
varied in a specified range by the lubrication system. The Roll Bite Lubrication
system incorporates a built-in automation system for operating it automatically
matching with the biting condition of the mill. Significant reduction in roll force,
power and roll wear have been achieved with the application of lubrication using Pilot
RBL system in hot rolling mills ensuring the prospect of wide industrial application.