FORM 2
THE PATENT ACT 1970 (39 of 1970)
The Patents Rules, 2003 COMPLETE SPECIFICATION (See Section 10, and rule 13)
TITLE OF INVENTION
AN IMPROVED STOPPER ROD MECHANISM;

APPLICANT (S)
a) Name
b) Nationality
c) Address

ISPAT INDUSTRIES LIMITED INDIAN Company CASABLANCA - PLOT NO. 45, SECTOR - 11, CBD BELAPUR, NAVI MUMBAI - 400 614 MAHARASHTRA

3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes invention and the manner in which it is to be performed


A Device for Lifting and lowering a Stopper Rod in a casting Apparatus
Field of the Invention :
The present invention relates to the casting apparatus being used for casting of molten metal such as steel. More particularly it relates to a device for lifting and lowering a stopper rod in a casting apparatus for regulating the flow rate of molten metal discharged from a tundish during a continuous casting operation.
Prior Art:
The continuous casting of molten metal involves providing an available source of molten metal in a suitable vessel, for example, a tundish or ladle, which is located physically above a mold in the continuous casting apparatus. When using a tundish as the vessel for holding the molten metal, a flow of molten metal is discharged there from into the mold via a tundish discharge nozzle at a flow rate which is suitable for the casting conditions. The flow rate of molten metal being discharged from the tundish nozzle is controllably regulated by a stopper rod. More specifically, the stopper rod is moveable relative to the tundish nozzle between seated and unseated conditions. Thus, movement of the stopper rod relative to the tundish nozzle will selective adjust the annular orifice area defined between the stopper rod tip and the tundish nozzle through which molten metal is allowed to flow. Adjustably varying the effective annular orifice area will thereby in turn adjustably control over the flow rate of the molten metal being discharged from the tundish.
Stopper rods are well known for use in controlling molten metal (especially molten steel), flow from a tundish, into a mould and stopper rod is raised and lowered by a suitable mechanism positioned adjacent the tundish and can thereby be used to close fully or partially or to open fully the outlet from the tundish thus controlling flow of the metal from the tundish.
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The United States patent US6026997 discloses a stopper rod in the form of an
elongate molded body having a longitudinal bore has an attachment device for
attaching the stopper rod to a lifting and lowering mechanism. The attachment
device comprises a first sleeve to be molded in-situ in the stopper rod body to lie
coaxially with the stopper rod body in an annular recess surrounding and
coterminous with the bore, the sleeve having a pair of circumferentially-spaced
inwardly-directed, arcuate flanges, a connecting rod of diameter to fit into the
stopper rod bore and of length to extend outside the stopper rod while passing
through the first sleeve when the sleeve is in position in the stopper rod, the
connecting rod having a pair- of circumferentially-spaced, arcuate shoulders of size
to pass through the spaces between the flanges of tthe first sleeve, so that the
connecting rod may be passed through the first sleeve until its shoulders have
passed beyond the flanges of the first sleeve and then rotated until its shoulders are
in circumferential correspondence with the flanges, and a second sleeve of external
diameter to fit in the bore of the stopper rod and having at one end a pair of
circumferentially-spaced, arcuate, axially-extending projections, the projections
having an internal radius sufficient to accommodate the connecting rod through the
second sleeve and tlie projections being of a size to fit into the spaces between the
flanges of die first sleeve so that the shoulders of the connecting rod may be locled
beyond the flanges of the first sleeve.
Tlie United States patent US5695675 discloses an arrangement for connecting an elongated stopper rod made of a refractory material for a metallurgical vessel to a lifting device for the stopper rod is provided. The arrangement includes a stopper rod having an upper front side and an internal longitudinal recess extending there from, a support having one end for engaging the lifting device an another end for engaging the stopper rod in the internal longitudinal recess. The stopper rod includes a housing that laterally widens a portion of the longitudinal recess, the housing having an upper boundary surface transverse to the longitudinal axis of the stopper rod and having side walls that taper from the upper boundary surface into the longitudinal recess. The support has at least one transverse opening in which
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blocking element is displaced across the longitudinal axis of the support so that the blocking element is releasably retained entirely within the cross section of the support during insertion of the support within the stopper rod in an insertion position and extends from the cross section and engages behind the upper boundary surface in a locked position. A releasable stop is provided on the support and upper front side of the stopper rod. The support can be easily and non-destructibly removed from the stopper rod and, when the stopper rod becomes worn, a new stopper rod can be mounted on the same support.
Further some of the conventional arrangements for lifting and lowering of stopper rod consist of Bush and Shaft and Keyway type arrangements to facilitate the linear motion and avoid rotational inovement of the shaft. Bush was made of Bronze v/ith four equally sized key slots outside and inside diameters whereas shaft is provided with keys which are moderately large. This key type arrangement has following limitations and because of it repetitive breakdowns in such mechanism are observed which ultimately adversely affects the productivity.

Limitations/ Problem Statement Effect
• Horizontal and Vertical Play > 7-S mm • Excessive time in centering the
MOMOBLOCK over SEN Port
• Uneven Erosion of MONOBLOCK causing
Frequent Rising in Stopper Position.
• Substantial variance in Setting Initial Zero to 50 rnm • Difference of more than lOmm over Zero set
at the time of fixing & actual read by PLC.
• Little Space to control MLF if Initial Zero is
well above 50mm
• Less Campaign Life (Life Between two successive Overhauling) • Frequent Overhauling is required.
• Difficulty in replacing Brass Bushes.
Hence it needed to provide a new mechanism for lifting and lowering a stopper rod which will address and obviate all the problems associated with prior art arrangements available for lifting and lowering of the stopper rod.
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Objectives of the Invention :
The main object of the present invention is to provide a device for lifting and lowering a stopper rod which obviates all the drawbacks associated with the prior art mechanisms available for lifting and lowering of stopper rod.
Another object of the invention is to provide a device for lifting and lowering a stopper rod for regulating the flow rate of molten metal discharged from a tundish during a continuous casting operation.
Yet another object of the present invention is to provide a device for lifting and lowering a stopper rod which ensures precise and controlled movement of stopper rod.
Yet another object of the present invention is to provide a device for lifting and lowering a stopper rod which has less brealxlowns in operations and thereby ensures long life.
Yet object of the present invention is to provide a device for lifting and lowering a stopper rod which operates automatically as well as manually.
Statement of the Invention :
Accordingly in order to achieve the above mentioned objects the present invention provides a device for lifting and lowering a stopper rod in a casting apparatus for re-gulating the flow rate of molten metal discharged from tundish during continuous casting process, said device comprises:
an elongated frame, said frame consists of first outwardly projected structure at the top, second outwardly projected structure at middle and third outwardly projected
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structure at the bottom,, said first and second outwardly projected structures having bore at the middle;
a pair of precision shaft being fitted in the pair of linear bearing, said shafts along with bearing are fitted in between said first and second outwardly projected structures of the frame;
main shaft being connected to stopper rod and thereby controlling the movement of the stopper rod, said main shaft is connected withi said bearings by means of at least two holding clamps, vertical movement of said main shaft is controlled by said bearings;
hydraulic cylinder being placed at the bottom of said main shaft to ensure the automatic lifting and lowering of the main shaft;
a hand lever with toothed segment and gear rack for manual lifting of said main shaft; and
a bracket arm for connecting said main shaft and stopper rod.
Brief description of the Drawings :
Figure 1 : Shows the device for lifting and lowering a stopper rod in a casting
apparatus in accordance to present invention. Figure 2 : Shows the enlarged view of the portion "A" shown in figure 1.
Detailed description of the invention:
The above, and the other objects, features & advantages of invention will become apparent from following description read in conjunction with the accompanying drawings.
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A device for lifting and lowering a stopper rod is one of the important equipment being responsible for uninterrupted continuous casting in compact ship production. A device for lifting and lowering a stopper rod get fixed in tundish in casting apparatus before placing the tundish into the Tundish Car. Initially the stopper rod blinds the pouring opening of the submerged entry nozzle in the tundish bottom. Thereafter at the time of cast skirt the stopper rod lifted and lowered by means of the proposed device to open and/or close the pouring opening and at specified casting speed, to keep the mould both level constant. This flow of liquid steel into the mould to precisely controlled by stopper rod lifting and lowering device.
How referring to figure 1 and 2, a device (1) for lifting and lowering stopper rod in accordance to present invention comprises an elongated frame (2). This frame (2) consists of first outwardly projected structure (3) at the top, second outwardly projected structure (4) at middle and third outwardly projected structure (5) at the bottom. The first and second outwardly projected structures (3, 4) consists of circular opening at the middle. Dual precision shafts (6, 7) are provided which are being fitted in the pair- of linear bearing (S, 9). These shafts (6, 7) along with bearings (8, 9) are fitted in between first and second outwardly projected structures (3, 4) of the frame (2).
The device (1) further comprises a main shaft (10) which is connected to stopper rod (11). According to the present invention die movement of the main shaft (10) controls the movement of the stopper rod (11). The vertical movement of the main shaft (10) is controlled by bearings (S, 9). The holding clamps (12, 13) connects main shaft (10) with bearings (8, 9). The holding clamps (12,13) consist of 1 guide bar (17) through which the main shaft (10) passes. Guide bar (17) passes through the bores of first and second outwardly projected structures (3, 4).
The device (1) can be operated in two modes fust is in automatic mode and other is manual mode. A hydraulic cylinder (14) is provided at the bottom of the main shaft (10) to ensure the automatic lifting and lowering of the main shaft. For manual
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lifting of main shaft (10) a hand lever (15) with toothed segment and gear rack (16) are provided.
A bracket arm (18) connects the stopper rod (11) with the main shaft (10). Main shaft (10) is connected to bracket arm (18) through guide bar (17). Also slip gauge 920) is provided for ensuring accuracy in the initial setting of the device (1) which ultimately eliminates the error.
The present invention is not limited to the above-described embodiments, and various alterations, modifications, and / or alternative applications of the invention may be possible, if desired, without departing from the scope and spirit of the invention, which can be read from the claims and the entire specification.All these possible alterations, modifications, and / or alternative appUcations of the invention are also intended to be within technical scope of the present invention.
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WE CLAIM:
1. A device for lifting and lowering a stopper rod in a casting apparatus for regulating the flow rate of molten metal discharged from tundish during continuous casting process, said device comprises:
an elongated frame, said frame consists of first outwardly projected structure at the lop, second outwardly projected structure at middle and third outwardly projected structure at the bottom, said first and second outwardly projected structures having bore at the middle;
a pair of precision shaft being fitted in the pair of linear bearing, said shafts along with bearing are fitted in between said first and second outwardly projected structures of the frame;
main shaft being connected to stopper rod and thereby controlling the movement of the stopper rod, said main shaft is connected with said bearings by means of at least two holding clamps, vertical movement of said main shaft is controlled by said bearings;
hydraulic cylinder being placed at the bottom of said main shaft to ensure the automatic lifting and lowering of the main shaft;
a hand lever with toothed segment and gear rack for manual lifting of said main shaft; and
a bracket arm for connecting said main shaft and stopper rod.
2. The device as claimed in claim 1 wherein said holding clamps comprises a guide bar through which said main shaft travels.
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3. The device as claimed in claim 2 wherein said guide bar passes through bores of said first and second outwardly projected structures.
4. The device as claimed in claim 2 wherein said main shaft is connected to bracket arm through said guide bar.
5. The device as claimed in claim 1 further comprises slip gauge for ensuring accuracy in the initial setting of the device.
6. A device for lifting and lowering a stopper rod in a casting apparatus as hereinbefore described and illustrated with reference to accompanying drawings.
Dated this 29fh day of May, 2008

HIRAL CHANDRAKANT JOSHI
AGENT FOR
ISPAT INDUSTRIES LTD.
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