MECHANICAL EDGE GUIDE SYSTEM AND METHOD FOR CONTROLLING SIDE
TRACKING OF STEEL STRIP IN PICKLING LINE
FIELD OF INVENTION
The present invention relates generally to continuous rolling mills for rolling cold metal
strip, and more particularly to an improved manually operated new edge guide system and
method for adjusting the strip edge relief in the edge region of the material being rolled.
BACKGROUND ART
It is known that in any continuous pickling line, there is no in-built strip guide system
installed in the pickling bath zone due to highly corrosive atmosphere (acid fumes) which
will damage the sensor and control system. Due to absence of. strip guide system and due
to process abnormalities like tension fluctuation, non-uniform gauge profile of feedstock
material, etc, the strip is often likely to shift laterally on both sides and colloid with the walls
of pickling bath. Subsequently it may lead to the damages of strip edges as well as the
walls of pickling bath.
Any continuous pickling line is conveniently divided into three sections. The entry section
comprises of pretreatment of strip like welding, scale breaking, washing and entry looper.
The pickling section consists of numerous pickling acid bath having different acid
concentration and temperature, are separated with granite dams for cascade flow of acid
from last tank to first tank. The delivery section consists of squeezing, rinsing, drying,
trimming, shearing with exit looper as given in flow diagram (Fig.1). Rinsing and drying of
pickled strips prior to the coiling is an important pre-requisite to achieve improved strip
surface. Usually these lines are equipped with strip centering device at the exit section
prior to the trimming, shearing and the upcoiler. This strip centering device cannot control
the side tracking of the strip in the pickling bath region.

The Continuous Pickling Line (PL-1) at Bokaro Steel Limited (BSL) was set up for pickling
of thicker gauge (5.0mm to 2.0mm) and wider (1860mm to 1250mm) hot rolled strip. The
line was not equipped with any edge guide system at the pickling bath region. A
mechanical roller type strip centering device installed prior to the trimming, shearing and
the upcoiler. This roller type strip centering device was quite far-off than the pickling bath
zone and was having no significant contribution towards controlling side tracking of strip in
the pickling bath zone. The main reason of side tracking or lateral shifting of the strip in the
pickling region was due to several factors like bad profile or camber of incoming HR strip,
development of non-uniform loading pattern in secondary scale breaker, misalignment of
entry and exit looper drum, tension fluctuations due to non-synchronizing of pinch rolls
before and after pickling region (P#4 & P#5) and malfunctioning of catemary loop control
system. The strip edges often gets damage due to abrasion with side walls of pickling bath
due to lateral shifting of the strip in the bath region. These damaged strip edges
subsequently damages the rubber coating of squeezer rolls and also sometimes leads to
strip breakage resulting to line stoppage and delay in production hours. There was no such
control over the strip side tracking due to process abnormalities during processing of strip
in pickling line. Therefore it leads to loss in production hours and poor strip edge/surface
quality as well as productivity due to side tracking of strip.
The prior art has sought to control the strip lateral shifting in various ways, for instance
some of the continuous pickling lines are equipped with automatic strip centering device at
the exit zone prior to the shear and before the upcoiler. The working principle of automatic
strip centering device is based on electro-hydraulic system. The light source is passed
from the bottom of strip edge portion and the amount of light received by the sensor
located above the strip edge portion. If 50% of the amount of light source is being
received, it is said to be the strip is in proper centre. If the receiving amount of light souce
is more or less than 50%, the sensor will convert the energy to electrical volt which will
actuate the position transducer through servo-valve. The position transducer will will
activate the cylinder for lateral adjustment of the coiler, which will help to coil the strip
without telescopicity. This automatic strip centering device has no contribution towards the
controlling of strip lateral shifting at the pickling bath zone of a continuous pickling line.

In order to prevent the strip edge damage and to improve strip surface quality, a manually
operated mechanical edge guide system has been designed and introduced in the Pickling
Line to arrest effectively the side tracking of strip in the pickling bath zone and to improve
the strip edge and surface quality
SUMMARY OF THE INVENTION
For any continuous pickling line, the HR strips are passed through numerous mineral acid
baths of different concentration and temperature. The acid penetrates through the cracks
of scale and reacts chemically with the base steel metal. This chemical reaction dislodges
the chemical bonding between scales and base material of steel. The scale cracking is
propagated by bending and unbending of strip surface through scale breaker or stretch
leveler prior to the entry of pickling bath.
The Pickling Line -1 of Bokaro Steel Limited was installed during 1976 for pickling of
thicker and wider HR steel strips. The line was not equipped with any strip centering
device prior to the pickling bath. Sometimes, the strip was getting lateral shift due to bad
profile / camber of HR strip or tension fluctuation or non-uniform loading at scale breaker.
This was resulting in damages of strip edges when the strip was colliding with the side
walls of acid bath. It was also damaging the rubberized portion of the squeezer roll after
the pickling to squeeze out the acid carry-over on the strip surface after completion of
pickling process. As a result of non-uniform squeezing, the strips were getting side-
tracked. Strip surface quality of pickled strip was detonated due to acid-carry over on the
pickled strip surface.
In order to prevent / arrest the strip side tracking problem, an efficient and effective
manually operated mechanical edge guide system was designed and installed between
last acid tank in the pickling region and prior to squeezing unit. Damages of strip edges
could be avoided and acid carry-over on strip surface was reduced to substantial amount
resulting in improvement in strip surface quality.

Therefore the principle object of the present invention is to provide an improved manually
operated new edge guide system and method for arresting lateral shifting of the strip and
to avoid the edge damage of the strip being pickled.
The new improved mechanical edge guide system consists of at least one mechanical
drive comprising an arrangement of lead screw, screw nut, guide arm and handle wheel.
The mechanical drives like lead screw, screw nut are used for metered adjustment
between the guide arms for guiding for all width ranges of strip being processed. The guide
arm, mechanical units and supporting structure are configured for overcoming the axial
thrust due to lateral shifting of strip. Moreover the guide pin is used for the purpose of
taking care of abrasion of strip edge and further configured for easy fixing and removal of
guide pin in the guide block
The hand-wheel drive is used for the purpose of easy adjustment in manual operation
The mechanical edge guide system could be mounted between last acid tank and
squeezing unit for the arrest lateral shift of strip at the pickling tanks.
As per another object of the present invention the edge guide system is configured for
guiding the strip to the centre of the bath.
As per yet another object of the present invention the edge guide system is configured for
controlling the lateral shifting of strip while processing maximum and minimum width of the
strip.
Still another object of the present invention the edge guide system is configured for
metered movement of the guide arm
As per one of embodiment of the present invention the edge guide system is configured for
avoiding the strip edge damage due to collision with side walls of pickling bath

As per another exemplary embodiment of the present inventions the edge guide system is
configured for avoiding damage of Squeezer roll assembly for effective squeezing effect
and arresting acid carry over on strip surface
As per yet another embodiment of the present invention the edge guide system is
configured for retrofitting to line logistics with new frame and mounting arrangement
As per another object of the present invention the edge guide system is configured for
easy maintenance and trouble free operation with low investment cost
The attainment of the foregoing and related objects, advantages and features of the
invention should be more readily apparent to those skilled in the art, after review of the
following more detailed description of the invention, taken together with the drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention will be better understood by reference to the following description, taken in
connection with the accompanying drawings, in which:
FIG. 1 is a flow diagram of continuous pickling line - 1 drawing in accordance with the
present invention;
FIG. 2 is a line diagram of continuous pickling line - 1 drawing in accordance with the
location of present invention
FIG. 3 is a schematic diagram of automatic strip centering device in accordance with the
prior art
Fig 4(a) illustrates the front view of the mechanical strip guide assembly drawing in
accordance with the present invention;

Fig 4(b) illustrates the plan view of the mechanical strip guide assembly drawing in
accordance with the present invention;
FIG. 5 is a schematic diagram (component wise) of the mechanical strip guide system at
the pickling line in accordance with the present invention;
DETAILED DESCRIPTION
The recent trend is for producing defect-free and clean cold rolled steel (CR) strip. The hot
rolled (HR) steel strips are produced by hot rolling of hot steel slabs. The hot rolled strips
are subsequently cold rolled to achieve the desired strip thickness, mechanical properties
and surface quality of the finished cold rolled product. During hot rolling process, the oxide
scales are formed on the strip surface. The oxide which are time and temperature
dependant exposing to oxidizing atmosphere. Three types of tenacious oxides like wustite
(FeO), magnetite (Fe3O4) and hematite (Fe2O4) are formed at the sub-surface/surface of
the steel strip during hot rolling. These oxides are very hard and abrasive in nature, which
are to be removed prior to the cold rolling process. If these scales are not removed, they
may score the roll as well as strip surface due to high abrasion during cold deformation
and loose scales may also picked up by the rolls and subsequently embedded on the strip
surface causing rolled-in-scale defect. However, prior to the cold rolling process, these
scales are removed from the hot rolled (HR) strip surface by chemical dissolution in the
mineral acids, known as pickling process.
A new manually operated mechanical edge guide system has been designed, developed
and installed in the pickling line (PL-1). It was fitted between last tank of pickling bath and
squeezing unit, consisting of two sets of squeezer roll assembly (Fig 2). The edge guide
system consists of lead screw shaft, screw nut, guide carriage assembly, guiding support
pin, end support assembly, supporting pipe, hand wheel etc. The entire assembly was
mounted on the base frame on both the ends of supporting frame/ structure as shown in
Fig. 4a & 4b.

The lead screw shaft (Item 01 in Fig 4a & 4b) is made up of corrosion resistant steel rod of
100 mm diameter. The shaft has square type male thread of 2 TPI (thread per inch). Both
the ends are having opposite threads like the drive side was having right hand (RH) thread
and the left hand (LH) thread in the other side. The threaded portion of the shaft was
designed and calculated for the maximum and minimum traverse of guiding carriage
assembly to take care of maximum and minimum strip width processing. Ends of the lead
screw shaft were fitted with pedestal bearing, which were mounted on the end support
assembly. On the drive side, the shaft is protruded and fitted with hand wheel with the help
of square key for rotation of the shaft in clock-wise and anti clock-wise direction. The
pedestal bearings are bolted with end support platform. The end support assembly is fitted
to the mounting base frame/structure on both the side.
The screw nuts (Item 02 in Fig 4a & 4b) are fitted to the threaded portion of the lead screw
shaft and having matching threads of the lead screw shaft with close tolerance. The screw
nuts are mounted and welded on the guide carriage assembly. The space between the
guide carriage assemblies would increase during anti clock-wise rotation of lead screw
shaft and the space would decrease during clock-wise rotation of lead screw shaft. The
matching screw nuts are to be fitted to the respective ends of the lead screw. The screw
nuts are to be kept at the starting of the threaded portion for minimum width. The protruded
portion of the drive side of lead screw shaft, the hand-wheel(ltem 09 in Fig 4a & 4b) is
being fitted with the help of key.
The guide carriage assembly (Item 04 in Fig 4a & 4b) consists of the platform, side support
frame and guide pin holder with guide pin. The guide carriage platform is being fabricated
from 20mm thick plate with two holes of 100mm 0 for guide pin fixing. The side support
frame is made up of steel block having hole of 105 mm 0 through which two numbers 100
mm 0 seamless pipe had to support the guiding assembly as well as to arrest the lateral
twisting of the assembly. The side support frame is welded on the guide carriage platform.
Two numbers of roller type bearing are fitted in the top and bottom portion of guide pin
holder, made up of 100 mm 0 seamless pipe. These guide pin holder assembly is being

welded at the bottom part of the guide carriage platform with proper bracing just beneath
the holes of guide pin in the platform.
The guide pin (Item 03 in Fig 4a & 4b) was made up of high strength, high resistant to
abrasion and anti-corrosion stainless steel. The guide pins are having blunt head i.e, the
guide pin can be rested on the top of guide carriage platform. The guide pin is fitted
through the roller from the top for allowing rotational movement of the pin and inserted
inside the pin holder frame, which is welded to the bottom of the guide carriage assembly.
The guide pin is replaced from top of the guide carriage assembly (Item 04 in Fig 4a & 4b)
and freely suspended portion of pin would guide the strip edges.
The end support assembly (Item 05 in Fig 4a & 4b) comprises of end support platform,
holding block of support guide pipe, arrester of guide pipe and pedestal bearing. The end
support assembly is being fitted on the mounting base frame (Item 06 in Fig 4a & 4b) with
the help of bolts and also tag welded. It should act as a rigid end support for the
mechanical edge guide system. The end support platform is made up of 30mm thick plate
on which the holding block of support guide pipes are properly welded. The holding block
is made up of 20mm thick plate having a machined hole of 105mm 0 for insertion of guide
pipe through it. After fixing of guide pipe to the holding block, the end of the guide pipe is
locked with arrester in order to arrest the lateral movement of guide pipe. The pedestal
bearing (Item08 in Fig 4a & 4b) is being bolted to the end support platform and provides
the end support of the lead screw shaft.
The support guide pipe (Item07 in Fig 4a & 4b) is made up of 100 mm 0 Seamless pipe
(schedule 40) to take the entire dead load of suspended guiding carriage assembly. All the
holes made in the holding block of guide pipe are machined finish with close tolerance of
2-3 mm than the outer diameter of the guide pipe. The two numbers 100 mm 0 supporting
guide pipes are fixed at the ends of two mounting base frame with some locking
arrangement in order to arrest the lateral shifting of the supporting guide pipe.

This mechanical edge guide device has arrested the lateral shifting of strip, prevented the
damage of strip edges, and avoided strip breakage caused by abrasion with the tank wall
due to side tracking of strip. It also avoided the damages of squeezer roll rubber lining and
helped to reduce residual acid carry-over on the strip surface by effective squeezing. It has
also helped to produce better and cleaner pickled strips in Pickling Line -1.
Steps involved in Assembly of Components:
The following steps are involved for assembling the components of mechanical edge guide
system
1. The guiding carriage platforms are prefabricated as per drawing and the support
block for guide pipe is being welded on the platform. The guide pin holder for guide
pin is pre-fabricated with rollers and welded to the beneath of the platform. The hole
on the platform matches in the same line to the guide pin holder.
2. The end support platforms are pre-fabricated as per drawing and the support
holding block for guide pipe is being welded.
3. The support guide pipes are to be fitted through the machined holes of guide
carriage platform and end support platform.
4. Then the guide pipes are being locked at both the ends with the help of arrester,
which are welded at the end support platform.
5. The respective matching screw nuts are fitted to the threaded portion of the lead
screw shaft.
6. Then the screw nut in the lead screw shaft is to be adjusted for minimum width.
7. The pedestal bearings are fitted to the ends of the lead screw shaft.
8. The entire assembly of lead screw shaft, screw nut and pedestal bearing is being
placed at the top of the end support platform. The pedestal bearings are bolted to
the end support platform.
9. The non-drive side of the lead screw shaft is being locked with some another
arrester for arresting lateral shifting of lead screw shaft. In the potruted portion of
the drive side of lead screw shaft, the hand-wheel is being fitted with the help of
key. The key is being tightly fitted in the half key-way of the hand-wheel and lead
screw shaft end(drive side).

10. The guide pins are inserted from the top of the guiding carriage platform for proper
centering.
11. Then proper leveling of the screw nut base with the guiding carriage platform and
finally the screw nut base is being welded to the top of the guiding carriage platform.
Now it becomes total mechanical edge system.
12. Proper lubricants to be provided between the screw nut and lead screw threaded
portion during fitting. Lubricants also to be provided at the outer surface of guide
pipe and machined holes of the guiding carriage assembly for smooth traverse of
guiding carriage assembly. Lubricants also to be provided to the rollers of the guide
pin holder for free rotational movement of guide pin.
Working Principle:
1. Firstly the space between guiding pins to be kept at maximum gap before the
mechanical edge guide system putting in operation.
2. As soon as the strip processing starts, the operator has to closedown the gaps
between the two ends of guide pins by clockwise rotation of the hand-wheel suiting
to the strip width. There should be nominal clearance of 5mm to be kept between
the pin outer surface and strip edge.
3. Usually campaign processing of same width strip takes place. When there is any
change in width of strip, it is being intimated through announcement or hooter from
pulpit. Immediately the operator moves to the edge guide system and adjust the
gaps between the guide pins as per information. Then again the campaign of same
strip width processing takes place. As an average the changes of strip width takes
place 3 to 4 times in a shift of eight hours.
4. When there any damage or change of guide pin requires, the space between
guiding carriage assembly is to be made maximum. The guide pins are lifted up
from the top and replaced by new one. Again the adjustment of the gap of guide
pins to be carried out according to the strip width processing.

Significance of Manual Operation:
• The edge guide system is being installed at the end of final pickling tank, which
contains 20 - 22% v/v of H2SO4 solution at a temperature of 90 - 95°C. The
environment of this region is highly corrosive acid fumes atmosphere and no
automatic sensors will be operative for a prolonged period. It will be highly
maintenance prone.
• Physical observation of gap adjustment and strip edge condition is an important
quality parameter
• However the rotational drive can be automated through drive gear box and motor,
which can be controlled from a distance or pulpit.
Field Trial Results:
With the commissioning of mechanical edge guide system, the following technological
improvements achieved;
> Lateral shifting of strip due to bad profile, tension fluctuation and non-uniform
loading pattern in scale breaker has been arrested
> Damage of side wall of pickling bath and squeezer rolls due to side tracking of strip
has been avoided
> Edge damage and strip breakage in pickling region has been reduced
> Line delays on account of side tracking of strip has been reduced
> Line speed has been increased by 10%
> Productivity has been improved by 10%
> Strip surface reflectance has been improved by 20% by effective arresting acid
carry-over
> Ease to maintenance with trouble-free operation has been achieved
Prospects for Utilization / Commercialization:
(a) SAIL Plants (b) Other Steel Plants in INDIA

Improvement in techno-economics indices:
> Reduced delays on account of side tracking of strip with financial impact of Rs 1.0
crore
> Helped to Increase productivity by 10% with financial impact of Rs 0.8 crore
> Higher cost-benefit ratio (BCR = 30:1)
Numerous characteristics and advantages of the invention covered by this document have
been set forth in the foregoing description. It will be understood, however, that this
disclosure is, in many respects, is only illustrative. Changes may be made in details,
particularly in matters of shape, size, and arrangement of parts without exceeding the
scope of the invention.

We Claim:
1. An improved manually operated mechanical edge guide system for controlling side
tracking of steel strip in pickling line comprising of:
at least one mechanical drive arrangement of lead screw, screw nut, guide
arm and handle wheel wherein the guide arm, mechanical units and supporting structure
are configured for overcoming the axial thrust due to lateral shifting and a guide pin used
for the purpose of taking care of abrasion of strip edge.
2. An improved manually operated mechanical edge guide system as claimed in claim
1, wherein the lead screw, screw nut are used for metered adjustment between the guide
arms for guiding for all width ranges.
3. An improved manually operated mechanical edge guide system as claimed in claim
1, wherein the guide pin is configured for easy fixing and removal from the guide block.
4. An improved manually operated mechanical edge guide system as claimed in claim
1, wherein the hand-wheel drive is used for the purpose of easy adjustment in manual
operation.
5. An improved manually operated mechanical edge guide system as claimed in claim
1, wherein the mechanical edge guide system is mounted between last acid tank and
squeezing unit for the arrest lateral shift of strip at the pickling tanks.
6. An improved manually operated mechanical edge guide system as claimed in claim
1, wherein the edge guide system is configured for guiding the strip to the centre of the
bath.

7. An improved method for manually operated mechanical edge guide system for
controlling side tracking of steel strip in pickling line comprising the steps of;
guiding the strip to the centre of the bath;
controlling the lateral shifting of strip while processing maximum and minimum width
of the strip;
controlling the metered movement of the guide arm; and
avoiding the strip edge damage due to collision with side walls of pickling bath
8. An improved method for manually operated mechanical edge guide system as
claimed in claim 7 further comprising the step of avoiding damage of Squeezer roll
assembly for effective squeezing effect and arresting acid carry over on strip surface
9. An improved method for manually operated mechanical edge guide system as
claimed in claim 7 wherein the system is configured for retrofitting to line logistics with new
frame and mounting arrangement and easy maintenance and trouble free operation with
low investment cost.
10. An improved manually operated mechanical edge guide system for controlling side
tracking of steel strip in pickling line, substantially as herein described with particular
reference to accompanying drawings.

The present invention relates generally to continuous rolling mills for rolling cold metal
strip, and more particularly to an improved manually operated new edge guide system and
method for adjusting the strip edge relief in the edge region of the material being rolled.