FIELD OF THE INVENTION

The present invention generally relates to Cross Piercing Elongation (CPE)
system in a seamless steel manufacturing plant. The present invention in
particular relates to a method for retraction of a diescher disc guiding hot pellet
billet in cross piercing elongation process so that the disc does not develop crack
due to continuous high temperature sustained during the time of power
interruption. More particularly, the invention relates to a method of safe guarding
a guiding disc from developing crack during power failure in a process of tube
manufacturing.
BACKGROUND OF THE INVENTION
In the process of seamless steel tube manufacturing in a cross piercing
elongation method, two rollers and two guiding discs are used for formation of
the steel tubes. In this process, two rollers are driven by using induction motors
which rotate at constant speed. Two guiding discs are rotated by top mounted
motor runs at variable speed based on the requirement. During the
manufacturing process, the hot billets coming out of a Rotary hearth furnace
via the roller conveyors are pushed into the CPE using an entry pusher. The
Entry pusher is an arrangement for pushing a hot billet till it touches the rolls.

Once the billet makes a contact with the roll and disc, the steel are formed in a
mandrel. The temperature at this point is around 1200 deg.
During this process, the discs are cooled with cooling water. During a power
failure, the flow of cooling water gets stopped. Rotation of the discs and rollers is
also stopped. In case, the rolling is in progress and the power failure occurs , the
hot billet gets inside the rolls and the discs, wherein cooling water also will not
be available. Because of the continuous contacts of the roll with the hot billet,
the roll will crack requiring replacement of the disc, which causes a huge
production loss. If the disc remains in contact with the hot billet for more than
10 second, the cracking of the roll disc occurs.
US 20140231115A1 describes a pile-driving apparatus which includes a diesel
hammer pile driver having a cylinder, and a piston and a striker displaceably
guided therein. A combustion chamber opens into a fuel feed device for
introducing a predetermined amount of fuel into the combustion chamber during
each working cycle. A disengagement apparatus axially displaceable on the
cylinder outside is disposed within the cylinder, to raise the piston, has a driver
introducible into a piston undercut, through a piston recess, and has an
operating lever for pivoting the driver into the cylinder space if a collision with
the engagement cam occurs. A disengagement cam on the cylinder above the
engagement cam pivots the driver out of the cylinder space if the operating lever
collides with the disengagement cam. The engagement cam and/or the operating
lever is configured for movement out of the collision region of the operating lever
or of the engagement cam.

In US20140191072A1 2014-07-10 entitled MULTI-STAGE RETRACTABLE CORD
WINDER DEVICE, discloses a retractable cord winder device, which has a front
cover with a center shaft, a spiral spring, a spool with a spool divider with a
flanged hook dividing the spool chamber into equal halves for efficient and
minimal noise cable coiling, oval sliding positioning sliding disc, and a rear cover
with concave recess to hold the oval positioning sliding disc with positioning
stopper. The front cover is mounted with the rear cover through the center shaft
via a center hole of the rear cover where there are symmetrical openings on both
ends for cords folded in half to be attached to the flanged hook and retracted
upon pulling down.
US 8432775B2 2013-04-30 entitled Motor driving circuit teaches VCM driver
driving a VCM. A DC/DC converter (switching regulator) receives a power supply
voltage from an external circuit, and generates a stabilized voltage. Linear
regulators each receive a power supply voltage from an external circuit, and
each generates a stabilized voltage. A shock detection circuit detects vibration of
a device mounting the driving circuit. A power monitoring circuit monitors the
power supply voltage, and generates a power-on reset signal which is switched
to a predetermined level whenever the power supply voltage is cut off. An ADC
converts the back electromotive voltage that occurs at the VCM into a digital
signal. A serial interface receives data from an external host processor, which is
used to control the driving circuit. Cutoff circuits are arranged between the
capacitors, which are to be charged using the induced current that occurs at the
SPM, and the power supply terminal. When the power supply voltage is cut off,
each cutoff circuit disconnects the corresponding capacitor from the power
supply terminal.

JP 4811859B2 2011-11-09 entitled Control device and control method for a
magnetic disk and a magnetic disk. The invention provides a retract control
method capable of stably returning a head to a lamp position by performing set
speed control, and a magnetic disk control device. A VCM driver is made to
repeat the operations; performing reverse braking when the operation voltage is
a first voltage or more that is equal to or more than the lower limit operation
voltage of a control circuit for a given period responding to power-off; stopping
the reverse braking when the operation voltage becomes equal to or less than a
second voltage that is less than the first voltage and includes the lower limit
operation voltage, and performing the reverse braking when the operation
voltage recovers the first voltage by stopping the reverse braking. After the lapse
of the given period, the VCM driver is operated by a control voltage
corresponding to a difference between a retract control voltage and a detection
voltage corresponding to the counter electromotive voltage of a VCM coil.
US 2910146686A 2010-07-01 entitled MAGNETIC DISK DEVICE, proposes a
magnetic disk device capable of preventing a failure of a magnetic head and a
magnetic disk by preventing cut powder of a ramp from being scattered on a
recording surface of the magnetic disk. The magnetic disk device has: a head
gimbal assembly having a magnetic disk having a recording surface supported in
a rotatable manner, a slider including a head and a tab to make the head access
the recording surface of the magnetic disk; and a ramp provided around the
magnetic head to have a recording surface opposite plane facing a peripheral
part of the recording surface of the magnetic disk, an end face opposite plane

facing an end face of the magnetic disk, and a drawing pen for making the tab of
the head gimbal assembly slide. In the ramp, a portion of a side face adjacent to
the recording surface opposite plane and facing the magnetic disk in a rotation
direction retreats downstream in the rotation direction of the magnetic disk to
make an acute angle between the retreated portion of the side face and a
tangent line of the periphery of the magnetic disk
Hence there is a need to develop a method to retract the disc i.e. within less
than 10 sec during a power failure to avoid the contacts of the disc with high
temperature billet in the process of steel tube manufacturing.
OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose a method of safe
guarding a guiding disc from developing crack during power failure in a process
of tube manufacturing.
A further object of the present invention is to propose a method of safe guarding
a guiding disc from developing crack during power failure in a process of tube
manufacturing, in which a solenoid valve for retraction of the guiding disc is
operated immediately upon identifying a power failure.

SUMMARY OF THE INVENTION
Accordingly, there is provided a method of safe guarding a guiding disc from
developing crack during power failure in a process of tube manufacturing.
During power failure condition, the pumps of the Cross Piercing Elongation
system are switched off. Thus, oil will be coming through the Non Return valve.
The top shaft of the accumulator is filled with Nitrogen and the bottom half is
filled with oil. Upon activating the pilot solenoid valve, the oil flows via the non-
return vale to the declamping cylinders .The Left Diescher Disc solenoid valve
and Right Diescher disc solenoid valve will receive the oil from the accumulator
and because of energisation of the Left Diescher Disc solenoid valve and Right
Diescher disc solenoid valve , the oil will go to the declamping cylinders . SO the
right and left diescher discs will be in will be declamped position and will be
moved away from the hot billet. All the above operation will be completed within
a period of less than 10 sec to eliminate the contact between DD, Roller and
billet. By the above disclosed method, the draw backs of the prior art are
eliminated and there is a substantial savings in man hour because of only one
hour time is required after power restoration for the continuous operation
instead of 2 shifts production loss .

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 Shows an existing hydraulic system with accumulator and solenoids
used during power failure condition.
Figure 2 Shows the hydraulic system with accumulator and solenoids during
power failure condition with Diescher Disc retraction mechanism according to the
present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
PRESENT INVENTION
Figure 1 Shows a prior art hydraulic system with accumulator and valves during
power failure condition
During power failure condition the Cross Piercing Elongation pumps are switched
off. So oil comes through a first Non Return valve (10) .The accumulator (9) top
half is filled with Nitrogen and bottom half is filled with oil. Due to the pilot
solenoid valve (8) in de-energized condition oil will not flow via a second non-
return vale (7) to the declamping cylinders (3, 4, 5 and 6).Thus, the disc will be
in clamped position and will be in contact with the hot billet during power failure.

Figure 2 Shows the hydraulic system with accumulator and valves during power
failure condition with implementation of a Diescher Disc retraction mechanism.
During power failure condition, the Cross Piercing Elongation pumps will be
switched off. So oil will be coming through the first Non Return valve (10) .The
accumulator (9) top half is filled with Nitrogen and bottom half is filled with oil.
Due to activation of a pilot solenoid valve (8) oil will flow via the second non-
return vale (7) to the declamping cylinders (3, 4, 5 and 6).The Left Diescher Disc
solenoid valve (1) and Right Diescher disc solenoid valve (2) will receive the oil
from the accumulator (9) and because of energization of the Left Diescher Disc
solenoid valve (1) and Right Diescher disc solenoid valve (2) the oil will go to
the declamping cylinders (3, 4, 5 and 6). SO the discs will be in declamped
position and will be moved away from the hot billet. All the above operations will
be completed within a period of less than 10 sec, so that the contact between
the DD, Roller and billet is avoided. By the above operation, the draw backs of
the prior art are eliminated and there is a substantial savings in man hour
because only one hour time is required after power restoration for the
continuous operation instead of 2 shifts production loss.

WE CLAIM :
1. A method of safe guarding a guiding disc from developing crack during
power failure in a process of tube manufacturing, the tube manufacturing
process implemented in a cross piercing elongation system having at
least a split type accumulation respectively filled with nitrogen and oil in
top left half and bottom half, a plurality of declamping cylinders; a first
non-return valve; a second non-return valve; a pilot solenoid valve; one
each left and right diescher disc solenoid valve; the method comprising
the steps of :
- switching off the pumps of the cross piercing elongation system to allow
flow of oil through the first non-return valve;
- activating a pilot solenoid valve to allow flow of oil to the declamping
cylinders via the second non-return valve;
wherein the left and right diescher disc solenoid valves receiving oil from the
accumulation upon energizing causing the flow of oil to the declamping
cylinders leading the disc solenoids to be move away from the hot billets, and

wherein the operations of safeguarding the disc valves upon power failure is
implemented within a period of about 10 seconds.