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HYDRAULIC ROLL SQUEEZING SYSTEM FOR ARRESTING CARRY- OVER
RESIDUALS ON COLD ROLLED STRIP
FIELD OF INVENTION
The present invention deals with a new improved hydraulically operated Roll
squeezing system for arresting the carry over residuals during degreasing operation of
cold rolled strip at Continuous Annealing Line(CAL). The invention concerns a system
for effective squeezing out residuals on cold rolled strip composed, for example, of
special steels and/or nonferrous metals in a CAL, in which the degreasing carried out
by Alkali cleanser in Cleaning section, determine the surface quality of the strip with
residuals after annealing operation. The invention also concerns an installation for
carrying out the process.
BACKGROUND OF INVENTION
Initially the roll squeezing system consists of 7 sets and are located after scrubbing
unit of Alkali dunk tank and Electrolytic Alkali cleaning tank, and finally after Spray
Rinsing tank. All the roll squeezing sets were having rubberised rolls and were
operated pneumatically. The pneumatic cylinders were supplied with industrial air of
pressure range 3.0 to 3.5 bar containing lots of contaminants like dust, moisture, etc.
Due to the use of contaminated industrial air, which often damages seals of cylinders,
resulted the non-uniform functioning of pneumatic cylinders, leading to non-uniform
squeezing along the strip width and resulting to excess residual alkali carry-over on
the strip surface and often side tracking of strip takes place and finally sometimes
resulted to strip breakage.
The main reason attributed to improper cleaning was due to poor performance of
degreasing and cleaning sections, which required modification/ upgradation of the
existing squeezing system. In order to improve strip surface cleanliness level, a
hydraulically operated Roll squeezing system has been designed and introduced in
order to effectively arresting the carried-over alkali solution and rinse water over the
strip surface.

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The recent trends for production of clean steel, which indicates the higher degree of
strip surface cleanliness of the Cold rolled (CR) strip / coils. The cleanliness of the CR
strip is primarily dependent upon the amount of oil and iron fines residues on the strip
surface. An emulsion coolant system used for cold rolling of steel which results in
some amount of emulsion are being carried-over on the strip surface during rolling.
The steel strips after cold deformation in Tandem Cold Mill, the rolled materials
becomes hard and brittle due to the elongated, distorted grain structure and
development of internal stresses takes place. These harmful effects leads to
unsuitable for further engineering applications of the CR strips. Therefore, in order to
remove all these effect, the strip is being annealed for the grain refinement of distorted
grain structure by recrystalization, release of internal stresses and to improve the
mechanical properties like ductility, softness, machinability, flatness, shape/profile of
the strip, etc. These cold rolled coils are annealed in the Continuous Annealing
Line(CAL). Therefore, the emulsion carry-over on the strip surface to be degreased
effectively in the cleaning section with the help of alkali cleanser and rinsing with hot
water prior to annealing process or otherwise potential carry-over will impair strip
surface quality and the downstream processes. The surface of CR strip is required to
be clean to facilitate coating, painting and plating of the strip by end-users and to give
on visual appeal of the finished product.
At CAL, pneumatically operated roll squeezing system was installed during 1991-92.
The existing roll squeezing system was found inadequate to arrest the emulsion carry
over on the strip surface due to non-uniform squeezing effect. As a result of non-
uniform squeezing, often the strips were getting side-tracked during process and
potential emulsion carry-over resulting to poor strip surface quality.
To take care of this problem, an efficient and effective hydraulically operated roll
squeezing system was designed and installed after Alkali Dunk Tank, Electrolytic
Cleaning Tank and Strip Rinsing Tank of CAL such that the carry-over residues on
strip surface may be reduced to substantial amount and resulting in improvement in
surface quality and strip surface reflectance.

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Therefore the essence of the present invention is to create a new improved
hydraulically operated Roll squeezing system for arresting the carry over residuals on
cold rolled strip at CAL.
SUMMARY OF THE INVENTION
Briefly stated, the foregoing and other objects are accomplished by the present
invention, which provides hydraulically operated Roll squeezing system for arresting
the carry over residuals on cold rolled strip during degreasing operation in CAL, in
which the first stand(s) carry out relatively large reductions, and the effectiveness of
degreasing and arresting carry-over on strip surface, determine the surface quality of
the annealed strip, along-with an installation for carrying out the process.
Accordingly the principle object of the present invention is to provide a new improved
Roll Squeezing system which is hydraulically operated.
Another object of the present invention is to provide uniform squeezing across the
width of the strip with substantially reducing the side tracking of strip.
As per an exemplary object of the present invention there is provided metered flow of
hydraulic oil for smooth and uniform movement of Top Squeezer roll.
As per another exemplary object of the present invention, the system is provided with
hydraulic cylinders on both ends for actuation of top squeezer roll.
As per another object of the present invention the system is provided with Hydraulic
power-pack for supply of pressurized hydraulic oil to the hydraulic cylinders
As per another embodiment of the present invention, there is provided hydraulic valve
stands to every squeezer roll set for hydraulic oil supply at constant pressure.

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As per another object of the present invention the system is equipped for arresting
residual carry over completely from the rolled strip surface by effective squeezing
effect
As per yet another object of the present invention a control panel is introduced in the
system for on/off operation of the system.
As per another exemplary embodiment of the present invention the system is provided
with retrofitting arrangement of hydraulic cylinders to existing location of Squeezer roll
frame with new mounting arrangement.
The modified roll squeezing system should be mounted after Scrubbing Unit-1,
Scrubbing Unit -2 and Rinsing Tank
As per another object of the present invention the system is made for an easy
maintenance and trouble free operation with low investment cost and high productivity.
As per another exemplary object of the present invention, the hydraulic cylinders
designed to take care of dead weight of Top Squeezer roll and very low speed of
cylinder movement for inching operation of top squeezer roll.
As per another object of the present invention, pulsation dampener with throttle and
check valves are incorporated in the system for meter-in flow hydraulic circuit.
These together with other objects of the invention, along with the various features of
novelty, which characterize the invention, are pointed out with particularity in the
claims annexed to and forming a part of this disclosure. For a better understanding of
the invention, its operating advantages and the specific objects attained by its uses,
reference should be had to the accompanying drawings and descriptive matter in
which there are illustrated preferred embodiments of the invention.

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BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The accompanying drawings schematically illustrate the principles of this invention, the
various views being as follows:
FIG.1 shows material flow diagram at continuous annealing line according to the
present invention;
Fig. 2 schematic view of continuous annealing line according to the present invention;
Fig. 3 shows schematic diagram of hydraulic power-pack according to the present
invention;
Fig 4 shows schematic diagram of valve stand arrangement according to the present
invention;
Fig. 5 shows schematic diagram of electrical connection in control panel according to
the present invention.
DETAILED DESCRIPTION
Usually prior Roll Squeezing system was being carried out with pneumatically
operated at the pressure of 3.0 to 3.5bar. The available industrial air are supplied to
the pneumatic cylinders. The piston end of the pneumatic cylinders are fitted to the
end support bracket of top squeezer roll. The clevis end of pneumatic cylinders are
fitted to the fixture on top of the end support bracket of top squeezer roll. The end
support bracket of top squeezer roll glides between the channel guide of the roll
stand/frame. The problem with industrial air is that it contains lots of dust /debris,
compressor oil, moisture and these carried contaminants in the air gets embedded and
subsequently produces scratches on the seals of the pneumatic cylinders. This leads
to non-uniform functioning of Squeezer Roll assembly which results to non-uniform
squeezing effect on the strip surface across the width. This non-uniform squeezing
effect on the strip surface leads to non-uniform pressure distribution across the width
of strip and often resulting to side tracking of causing line stoppage due to strip
breakage and delays. These pneumatic cylinders are highly maintenance prone due to
contaminated industrial air. The pneumatically operated roll squeezing system usually
provided after every degreasing and cleaning unit to arrest the carry-over of residuals
on the strip surface. The carried residuals due to inadequate squeezing gets oxidized

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during annealing process and results to poor strip surface quality with respect to
reflectance. Therefore ineffective pneumatically operated Roll Squeezing system leads
to the poor strip surface quality as well as effects productivity due to side tracking of
strip.
The Continuous Annealing Line (CAL) at Bokaro Steel Limited(BSL) was set up for
processing and annealing of thinner gauge (0.25mm to 0.50mm) cold rolled strip as
shown in Fig. 2. The continuous annealing line is conveniently divided into three
sections. The entry section comprising strip degreasing and cleaning section, the
furnace section and the delivery section in which annealed strip is re-coiled. Cleaning
or degreasing of cold rolled strips prior to the entry of the Annealing Furnace is an
important pre-requisite to achieve improved strip surface reflectance of annealed coils
as shown in Fig. 1.
Modified Emulsion Arresting System :
To overcome the aforesaid difficulties a new hydraulically operated Roll squeezing
system has been designed and installed in the places of 4 sets (after scrubbing unit of
Alkali dunk tank, Electrolytic Alkali cleaning tank and after Spray Rinsing tank)
operating in the pressure range 0 to 10bar. The system is equipped for arresting
residual carry over completely from the rolled strip surface by effective squeezing.
For providing uniform squeezing across the width of the strip with substantially
reducing the side tracking of strip and metered flow of hydraulic oil for smooth and
uniform movement of Top Squeezer roll a hydraulically operated roll squeezing system
is introduced. The modified roll squeezing system should be mounted after Scrubbing
Unit-1, Scrubbing Unit -2 and Rinsing Tank. The hydraulically operated roll squeezing
system consists of four units like hydraulic power station, valve stands, arrangement of
hydraulic cylinders and electrical panel/console.
Hydraulic power station :
The hydraulic power-pack of roll squeezing system is fitted over the oil reservoir ( 1m
X 1m X 0.8m) made-up of mild steel sheet of 6mm thickness with oil level indicator
and 3/4" drain valve. The power-pack consists of two hydraulic Fixed Displacement

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Vane type Pump-set(one operative and another standby), Pressure filter, return filter,
Solenoid control relief valve, Suction Strainer, Return filter, Check valve, Accumulator
bladder type, Solenoid operated Direction Control valve, Needle valve, pressure
reducing valve, Pulsation Dampener, Pressure gauge, Heat exchanger etc. which is
shown in Fig. 3. The controlled hydraulic oil in consideration to pressure and quantity
are being supplied to the valve stands.

SI No Item No Description
1 1 Oil reservoir
2 2 Drain valve
3 3 Oil fill Strainer
4 4 Breather filter
5 5 Return filter
6 6 Plate type Heat exchanger
7 8,9 Suction strainer
8 10, 11 Fixed Displacement Vane Pump
9 12, 13 Bell housing
10 14, 15 Flexible drive coupling
11 16, 17 Electrical Motor
12 18, 19 Flexible Hose coupling
13 20,21,23 Inline type Check valve
14 27 Pulsation dampner
15 28,34 Solenoid operated Directional Control valve
16 29 Bladder type Accumulator
17 32 Direct type Relief valve
18 38 Pressure gauge
Valve Stands:
The hydraulically operated roll squeezing system is provided with hydraulic valve
stands to every squeezer roll set for hydraulic oil supply at constant pressure. There
are 4 numbers of Valve stand. Each valve stand is catering to the two hydraulic
cylinders on both ends of Squeezer roll and are located close to the operating

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squeezing stand to take care of minimum pressure drop. The valve stand consists of
Solenoid operated Direction Control valve, Pressure reducing valve, manifold and
check valve given in Fig. 4.

SI No Item No Description
1 6, 7, 8, 9 Pulsation Dampner
2 10, 11, 12, 13 Modular Pilot- operated Check Valve
3 14,15,16, 17 Solenoid operated Directional Control Valve
Arrangement of hydraulic cylinders: The hydraulic cylinders designed to take care of
dead weight of Top Squeezer roll and very low speed of cylinder movement for inching
operation of top squeezer roll. The piston ends of hydraulic cylinders are fitted to the
ends of the end support bracket of top squeezer roll. The clevis ends of hydraulic
cylinders are fitted to the fixture on top of the end support bracket of top squeezer roll.
The end support bracket of top squeezer roll glides between the channel guide of the
squeezer roll stand/frame. The hydraulic cylinders are of 63ø X 30ø X 50 stroke
length. The metered movement of the actuating hydraulic cylinders has been
considered with proper pulsation dampner for uniform pressure distribution along the
strip width by the squeezer rolls for effective squeezing. The hydraulic cylinders have
retrofitting arrangement to existing location of Squeezer roll frame with new mounting
arrangement.
Electrical panel/console:
The electrical panel/console is located closed to the the Operator's desk for easy
handling of the system. The present system is equipped with a control panel for
switching operation of the system. The electrical Control panel consisting of control
and on / off switches for running of pump-set and actuation of selective Squeezer Roll-
set as given in Fig. 5.
Experimentally it has been found that the presently disclosed modified hydraulic roll
squeezing system shows an enhanced effect of arresting the residual carry-over on
the strip surface, moreover avoid the side tracking of strip and helps to produce better
and cleaner strips with improved surface reflectance. Furthermore the system is made

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for an easy maintenance and trouble free operation with low investment cost and high
productivity.
Field Trial Results :
With the commissioning of total modified Roll Squeezing system, the following
technological improvements achieved ;
 Arresting residual carry-over effectively from the rolled strip surface
 Reduced substantially side tracking of strip
 Reduction in delays on account of side tracking of strip
 Contributed towards the increased line speed by 10%
 Helped to improve productivity from 12.4t/hr to 14.4t/hr
 Improved strip surface reflectance from 80% to >90%
 Easy to maintain with trouble-free operation
Improvement in techno-economics indices:
 Reduced delays on account of side tracking of strip with financial impact of
Rs 0.60 crore
 Helped to Increase productivity from 12.4t/hr to 14.4t/hr with financial impact of
Rs 0.40 crore
 Higher cost-benefit ratio (BCR = 12:1)
Although the foregoing description of the present invention has been shown and
described with reference to particular embodiments and applications thereof, it has
been presented for purposes of illustration and description and is not intended to be
exhaustive or to limit the invention to the particular embodiments and applications
disclosed. It will be apparent to those having ordinary skill in the art that a number of
changes, modifications, variations, or alterations to the invention as described herein
may be made, none of which depart from the spirit or scope of the present invention.
The particular embodiments and applications were chosen and described to provide
the best illustration of the principles of the invention and its practical application to
thereby enable one of ordinary skill in the art to utilize the invention in various
embodiments and with various modifications as are suited to the particular use

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contemplated. All such changes, modifications, variations, and alterations should
therefore be seen as being within the scope of the present invention as determined by
the appended claims when interpreted in accordance with the breadth to which they
are fairly, legally, and equitably entitled.

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We Claim :-
1. An improved hydraulically operated roll squeezing system for arresting the carry
over residuals on cold rolled strip comprising of:
hydraulic cylinders on both ends for actuation of top squeezer roll;
hydraulic power-pack for supply of pressurized hydraulic oil to the hydraulic
cylinders;
hydraulic valve stands to every squeezer roll set for hydraulic oil supply at
constant pressure; and
electrical control panel for controlling operation of the system.
2. An improved hydraulically operated roll squeezing system as claimed in claim 1,
wherein hydraulic cylinders are designed to take care of dead weight of top squeezer
roll and very low speed of cylinder movement for inching operation of top squeezer
roll.
3. An improved hydraulically operated roll squeezing system as claimed in claim 1,
wherein the hydraulic power pack further comprises of two hydraulic fixed
displacement vane type pump-set (one operative and another standby), pressure filter,
returm filter, solenoid control relief valve, suction stainer, return filter, check valve,
accumulator bladder type, solenoid operated direction control valve, needle valve,
pressure reducing valve, pulsation dampener, pressure gauge, heat exchanger.
4. An improved hydraulically operated roll squeezing system as claimed in claim 1,
wherein each hydraulic valve stand consists of solenoid operated direction control
valve, pressure reducing valve, manifold and check valve.
5. An improved hydraulically operated roll squeezing system as claimed in claim 4,
wherein each hydraulic valve stand caters two hydraulic cylinders on both ends of
Squeezer roll and are located close to the operating squeezing stand.

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6. An improved hydraulically operated roll squeezing system as claimed in claim
4, wherein the system comprises of 4 hydraulic valve stands and the piston end of
hydraulic cylinders are fitted to the ends of the end support bracket of top squeezer
roll.
7. An improved hydraulically operated roll squeezing system as claimed in claim
4, wherein the clevis end of hydraulic cylinders are fitted to the fixture on top of the end
support bracket of top squeezer roll and the end support bracket of top squeezer roll
glides between the channel guide of the squeezer roll stand/frame.
8. An improved hydraulically operated roll squeezing system as claimed in claim
2, wherein hydraulic cylinders are of 63ø X 30ø X 50 stroke length.

9. An improved hydraulically operated roll squeezing system as claimed in claim 2,
wherein hydraulic cylinders have retrofitting arrangement to existing location of
Squeezer roll frame with new mounting arrangement.
10. An improved hydraulically operated roll squeezing system as claimed in claim 1,
wherein the metered movement of the actuating hydraulic cylinders has been fitted
with proper pulsation dampner for uniform pressure distribution along the strip width by
the squeezer rolls for effective squeezing.
11. An improved hydraulically operated roll squeezing system as claimed in claim 1,
wherein the electrical control panel consisting of control and on / off switches for
running of pump-set and actuation of selective Squeezer Roll-set.
12. An improved hydraulically operated roll squeezing system as claimed in claim 1,
wherein the system provides uniform squeezing across the width of the strip with
substantially reducing the side tracking of strip.

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13. An improved hydraulically operated roll squeezing system as claimed in claim 1,
wherein the system provides metered flow of hydraulic oil for smooth and uniform
movement of top squeezer roll.
14. An improved hydraulically operated roll squeezing system as claimed in claim 1,
wherein the system is mounted after Scrubbing Unit-1, Scrubbing Unit -2 and Rinsing
Tank.
15. A rolling mill fitted with an improved hydraulically operated roll squeezing
system for arresting the carry over residuals on cold rolled strip as claimed in any of
the preceding claims.

The present invention relates to an improved hydraulically operated roll squeezing
system for arresting the carry over residuals on cold rolled strip comprising of:
hydraulic cylinders on both ends for actuation of top squeezer roll;
hydraulic power-pack for supply of pressurized hydraulic oil to the hydraulic
cylinders;
hydraulic valve stands to every squeezer roll set for hydraulic oil supply at
constant pressure; and
electrical control panel for controlling operation of the system.