FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION (See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"An Automatic Electro Slag Strip Cladding Overlay Welding Systems for Flat ' Surface"
2. APPLICANT:
(a) NAME: Larsen & Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: Larsen & Toubro Limited
L&T House, Ballard Estate, MUMBAI-400001, Maharashtra State, INDIA
3. PREAMBLE TO THE DESCRIPTION:
PROVISIONAL COMPLETE
The following specification describes the The following specification
invention. particularly describes the invention and
the manner in which it is to be
performed.

An Automatic Electro Slag Strip Cladding Overlay Welding systems for flat
surface
Field of Invention
The present invention relates to welding system, more particularly, the present invention relates to an automatic Electro Slag Strip Cladding (ESSC) overlay welding system.
Background of the Invention
Electro Slag strip cladding (ESSC) is a more recent development of the strip surfacing technique. In the ESSC overlay welding process a strip electrode is continuously fed into a shallow layer of molten electro conductive slag. The heat which is needed to melt the strip, the slag-forming flux and the surface layer of the base metal is generated by the Joule's effect as a result of the welding current flowing through the liquid electro conductive slag. The ESSC strip process is started in the same way as a submerged arc cladding; the stabilization of the process into the ESSC mode is reached almost instantaneously,
Generally, at present the ESSC overlay welding is done manually by adjusting the boom motion of the crane. The rotational speed of the welding positioner is also adjusted manually for each and every weld overlay run. Further, the welding strip needs to be manually adjusted for every overlay welding run.
This increases cycle time, as the speed and position of the welding head needs to be adjusted manually. Further, grinding or dressing of multiple start and stop points in each overlay run is done to achieve smooth finish. Furthermore, as the system is manually adjusted, the welding quality depends on personal skills.

Objects of the Invention
Object of the present invention is to provide an automatic ESSC overlay welding system, which reduces human intervention, thereby increasing accuracy and reducing cycle time.
Another object of the present invention is to provide an automatic ESSC overlay welding system, which eliminates grinding and finishing process on the start and end points of overlay welding.
Statement of the invention
According to the present invention there is provided an automatic Electro Slag Strip Cladding (ESSC) overlay welding system for imparting corrosion resistance to a component, the system comprising:
a column and a boom manipulator for mounting a welding head thereover, the column is positioned vertically on the ground, and the boom is slidably secured over the column, wherein the welding head is secured to the boom and the boom operated by a first motor;
a welding positioner positioned below the welding head, the welding positioner having a supporting member and a table rotatably mounted on the support member, wherein the welding positioner is capable of holding and rotating a component on which the ESSC overlay welding is to be performed:
a sensor disposed over the supporting member and adjacent to the table. wherein the sensor is capable of sensing a position marked circumferentially on the table of the welding positioner;
a first variable frequency drive connected to the first motor reciprocating the boom over the column, wherein the first variable frequency drive is capable of

controlling the rotation of the first motor, thereby controlling the reciprocation of the boom;
a second variable frequency drive connected to a second motor coupled to the table of the welding positioner, wherein the second variable frequency drive is capable of controlling the rotation of the second motor, thereby controlling rotation of the component secured over the table;
an encoder disposed on the boom, the encoder capable of measuring distance travelled by the boom; and
a Programmable Logic Controller (PLC) connected to the first variable frequency drive, the second variable frequency drive, the sensor and the encoder, wherein upon receiving signal from the sensor, the PLC commands the first variable frequency drive to operate the first motor to move the boom, depending upon the position of the boom sensed by the encoder, the PLC commands the second variable frequency drive to change the speed of rotation of second motor, thereby changing the rotational speed of the component held over the table to make the linear welding speed constant.
Typically, wherein the sensor is a proximity sensor.
Typically, wherein a metallic cleat is secured on a circumference of the table to mark a position thereon.
Typically, wherein the component is a cylindrical tube sheet
Brief Description of the Drawings
The objects and features of the present invention will be more clearly understood from the following description of the invention taken in conjunction with the accompanying drawings, in which,

Figure 1 shows a schematic front view of an automatic ESSC overlay welding system in accordance with the present invention.
Detail description of the Invention
The foregoing objects of the invention are accomplished and the problems and shortcomings associated with the prior art techniques and approaches are overcome by the present invention as described below in the preferred embodiment.
The present invention provides an automatic Electro Slag Strip Cladding (ESSC) overlay welding systems. The system reduces human intervention, thereby increasing accuracy and reducing cycle time. Further, the system eliminates grinding and finishing, which was required at the start and end points of overlay welding of the prior art.
This present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.
Referring now to figure 1, schematic diagram of an automatic Electro Slag Strip Cladding (ESSC) overlay welding system (100) is illustrated. The system (100) includes a welding head (5), a column (12) and a boom (14) manipulator (10), a welding positioner (20), a sensor (30). a first Variable frequency drive (first VFD (40)), a second Variable frequency drive (second VFD (42)), an encoder (50), and a Programmable Logic Controller (herein after referred as "PLC (60)") and component (70).

The column (12) is positioned vertically on the ground/surface. The boom (14) is slidably secured to the column (12). A first motor (16) is secured to the boom (14) to slide the boom (14) horizontally over the column (12). Upon operating the first motor (16) the boom (14) slides over the column (12) by a rack and pinion arrangement configured therebetween. The welding head (5) is secured to an end portion of the boom (14). The sliding of the boom (14) enables the welding head (5) to move in a forward or reverse direction.
Further, the welding positioner (20) is positioned below the welding head (5), so as to perform ESSC overlay welding over the component (70). The welding positioner (20) includes a supporting member (22) and a table (24). The support member (22) is placed on ground/surface below the welding head (5). The table (24) is rotatably secured to the supporting member (22). The table (24) is provided with a second motor (26) to rotate the table (24) over the supporting member (22).
Further, the table (24) is also capable of holding the component (70) thereover. In an embodiment, the component (70) is a flat surface object circular in shape. A position (28) is marked on the table (24). The position (28) is marked by a metallic cleat on a circumference of the table (24). The sensor (30) is disposed over the supporting member (22) and adjacent to the table (24). More particularly, the sensor (30) is disposed adjacent to the table (24) to sense the marked position (28) using metallic cleat. In an embodiment, the sensor (30) is a proximity sensor.
Referring again to figure 1, the first VFD (40) is connected to the first motor (16) and to the PLC (60). The first VFD (40) is capable of controlling the rotation of the first motor (16), thereby controlling the reciprocation of the boom (14). Further, the second VFD (42) is connected to the second motor (26) and the PLC (60). The second VFD (42) is capable of controlling the rotation of the second motor (26), thereby controlling rotation of the component secured over the table (14). The encoder (50) is

disposed on the boom (14). The encoder (50) is capable of measuring distance travelled by the boom.
Further, the PLC (60) is connected to the first VFD (40), the second VFD (42), the sensor (30) and the encoder (50). The sensor (30) senses the (starting point) shifting of weld pass to next value. The sensor (30) senses start of the process of ESSC overlay welding and sends signals to the PLC (60). Further, the PLC (60) commands the first VFD (40) by sending signals to move the boom (14) in forward direction. Speed of movement of the boom (14) is also provided by the PLC (60) to the first VFD (40). The encoder (50) sends signals to the PLC (60) for each of the position of the boom (14) after the movement. Further, depending upon the position of the boom (14) the PLC (60) commands the second VFD (42) to change the speed of rotation of second motor (26), thereby changing the rotational speed of the component (70) held over the table (24).
Completion of one round of circular movement of the table (24) is sensed by the sensor (30) and similarly, the sensor (30) sends signals to the PLC (60) to complete another round of the ESSC overly welding over the component (70). The same process is continued till the completion of the ESSC overlay welding over the entire surface of the component (70) without any human intervention and pause.
The system (100) has advantages of eliminating human reduces human intervention, thereby increasing accuracy and reducing cycle time. Further, the system (100) enables elimination grinding and finishing process on the start and end points of
overlay welding.

Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or matter.
The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the spirit and scope of the invention; which is defined by the scope of the following description.

We Claim:
]. An automatic Electro Slag Strip Cladding (ESSC) overlay welding system for imparting corrosion resistance to a component, the system comprising:
a column and a boom manipulator for mounting a welding head thereover, the column is positioned vertically on the ground, and the boom is slidably secured over the column, wherein the welding head is secured to the boom and the boom operated by a first motor;
a welding positioner positioned below the welding head, the welding positioner having a supporting member and a table rotatably mounted on the support member, wherein the welding positioner is capable of holding and rotating a component on which the ESSC overlay welding is to be performed;
a sensor disposed over the supporting member and adjacent to the table, wherein the sensor is capable of sensing a position marked circumferentially on the table of the welding positioner;
a first variable frequency drive connected to the first motor reciprocating the boom over the column, wherein the first variably frequency drive is capable of controlling the rotation of the first motor, thereby controlling the reciprocation of the boom;
a second variable frequency drive connected to a second motor coupled to the fable of the welding positioner, wherein the second variable frequency drive is capable of controlling the rotation of the second motor thereby controlling rotation of the component secured over the table;
an encoder disposed on the boom, the encoder capable of measuring distance travelled by the boom; and
a Programmable Logic Controller (PLC) connected to the first variable frequency drive, the second variable frequency drive, the sensor and the encoder, wherein upon receiving signal from the sensor, the PLC commands the first variable frequency drive to operate the first motor to move the boom, depending upon the

position of the boom sensed by the encoder, the PLC commands the second variable frequency drive to change the speed of rotation of second motor, thereby changing the rotational speed,of the component held over the table to make linear welding speed constant.
2. The automatic ESSC overlay welding system as claimed in claim 1, wherein the sensor is a proximity sensor.
3. The automatic ESSC overlay welding system as claimed in claim 1, wherein a metallic cleat is secured on a circumference of the table to mark a position thereon.
4. The automatic ESSC overlay welding system as claimed in claim 1, wherein the component is a cylindrical tube sheet