Title of Invention

A TURNTABLE FOR OVERLAY WELDING OF ELBOW

Abstract The present invention relates to an overlay welding equipment to weld the entire inner surface of an elbow without changing the initial set up, covering all the four quadrants in one single set up. It provides a turntable which rotates around its vertical axis from 0° to 360° as available in conventionally method too. In addition, this turntable can also rotate 360° around the horizontal axis of the shaft on which it is mounted.
Full Text
FORM 2
THE PATENT ACT 1970
&
The Patents Rules. 2003
PROVISIONAL / COMPLETE SPECIFICATION (See section 10 and rule 13)
1. TITLE OF THE INVENTION
" AN IMPROVED TURN TABLE AS AN OVERLAY WELDING EQUIPMENT "

2. APPLICANT
(a) NAME

: LARSEN & TOUBRO LIMITED

(b) NATIONALITY : An Indian Company registered under the provisions of
The Companies Act, 1956.

(c) ADDRESS

: L & T House, Ballard Estate, MUMBAI-400 001, Maharashtra State, India

3. PREAMBLE TO THE DESCRIPTION

PROVISIONAL
The following specification invention.

Inscribes the

COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

4. DESCRIPTION (Description starts from page 2)


5. CLAIMS: Given on a separate page


6. DATE AND SIGNATURE: Given at the end of last page of specification.

7. ABSTRACT OF THE INVENTION: Given on a separate page
The following specification describes the nature of this invention.



The present invention relates to an overlay welding equipment to weld the entire inner surface of an elbow in a pipe joint. The purpose of the present invention is to make overlay welding of entire inner diameter (I.D.) possible in a single set up on a turntable. Turntables are conventionally used for the above purpose. More particularly it relates to a turntable, which can also rotate 360° instead of the normal 90 degrees about the horizontal axis X-X in addition to vertical axis Y-Y, so as to enable overlay welding of entire I.D. surface of an elbow in a single set up instead of four set ups required conventionally.
The present invention facilitates overlay welding of an elbow without changing the position of the elbow on the turntable from start to finish i.e. without repeated set ups of an elbow, to cover the entire internal surface by the material, deposited by welding process. The specially improved turntable helps in welding the entire inner surface from one face of the elbow to the other face along the axis to complete one pass. The next pass partially overlaps the earlier bead from one face to another until the entire inner surface is covered. The welding process continues till the first bead becomes adjacent. It also partially overlaps the last bead to complete the welding process. The entire inner surface is coated with a layer of suitable material (say stainless steel), which is of the required grade and thickness.
The present invention aims at reducing the number of set ups of the elbow on the turntable from a minimum of four set-ups to a single set up. Thus, the main object is to reduce the total set up time for overlay welding of an elbow to just about 25% of what is required conventionally, to minimize the use of skilled labour, to improve quality of welded layer, to improve productivity, and to economize this activity in general.
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The present invention is directed towards providing a turntable which rotates around its vertical axis from 0° to 360° as available in conventionally method too. In addition, this turntable can also rotate 360° around the horizontal axis of the shaft on which it is mounted. This 360° movement of the turntable is an improved step to replace the 90° movement of turntable that is in vogue.
PRIOR ART:
In prior art a conventional turntable, as shown in fig.1, is used for overlay
welding of elbows. The conventional machine is shown in fig.1. This consists of:
Mainframe -1
Table Top - 2
Sector Gears - 3 & 4
Table Support - 5
The component to be welded i.e. the elbow is placed on table top (2) and is secured firmly on it by means of clamps, nuts, bolts, etc. or special fixture. Before clamping the elbow, it is positioned properly by trial and error method or by means of special fixtures or by positioning aids in order to ensure the correctness of the set up for achieving welding run/pass from one face of the elbow to the other face along its axis by rotating the table about the Y-Y axis. The position of the electrode is kept such that it is 1G (perpendicular to the ground) position with respect to the location, which is to be welded. The welding pass starts from one face and ends at the other face of the elbow. During the first run the table is exactly horizontal, whereas for the second run the table is slightly inclined say by an angle of 5 degrees or so. The electrode which also gets inclined is readjusted in the 1G position with respect to the new location to be welded and welding is done from one face to another as had been done earlier. This inclination of the table and subsequent welding passes are carried out everytime. Such passes are repeated many times over starting from one face and ending at the other face of the elbow. In this way the first quadrant i.e. 25%
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of the job is completed. Thus, welding on 0 degrees to 90 degrees of the elbow are covered. The elbow is set up for the second time to complete the second quadrant. Similarly, two more set ups are required to complete the third and the fourth quadrant.
During each welding run, the welding bead formed by each pass is required to be parallel to the axis of the elbow so that not even one sq.mm of area is left uncovered by the protective coat that is deposited by this welding process. Each welding pass/run is also adjusted in such a fashion that it partially overlaps the bead from the earlier pass/run. In case, even a few sq.mm. of the inside surface of the elbow is left uncovered, it may lead to corrosion of the inner surface by the corrosive fluids/gases that flow through it while in operation. Such corrosion in normal use is very severe; it may drastically reduce the life of the systems, thinning of elbow wall etc. Such corrosion may also lead to premature failure, accidents, explosions and the like. Hence, the corrosion should be avoided under all circumstances.
Deficiencies of the Prior Art:
1. The top table can only be rotated through an angle of 90°.
2. Due to the above constraint, the set up of elbow is required to Joe made at least four times, for carrying out welding in four different quadrants.
3. The entire process requires a higher cycle time.
4. If the setting is not accurate the welding quality will not be up to the mark as the weld beads will not be parallel to each other.
5. Setting up of elbows is a skilled job; hence skilled manpower is required to work four times on each elbow.
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Description of the invention:
With a view to overcome the deficiencies found in the prior art, the present invention is introduced. The present invention consists of mainly of two rotating parts-
1. The upper part is a circular/rectangular frame called the table, on which the elbow is mounted and is rotated by a motor. Its axis Y-Y of rotation is vertical, when the table/frame is in horizontal position. The axis of rotation can change depending on the orientation of the frame.
2. The lower part is the shaft supported at both ends by taper roller bearings to take radial as well as thrust loads. The table is mounted on this shaft. The table can be rotated through 360° with the help of motor fitted with a worm-worm wheel arrangement. The rotational axis is horizontal.
An improved turntable for overlay welding of elbows which comprises of a table mounted on a shaft which in turn is held between taper roller bearings fitted in a rigid frame for rotating the table about X-X axis from 0 degree to 360 degrees for overlay welding of entire inner surface covering all the four quadrants; as done conventionally, the table can also rotate from 0 degree to 360 degrees about axis Y-Y for welding the inner surface of the elbow from one face to another; the entire inner diameter (I.D) is covered by welded beads which partially overlaps the earlier bead; after each welding run the table is slightly inclined say by 5 degrees and the electrode is adjusted to 1G position i.e. perpendicular to ground and accordingly the welding process is carried out again from one face to another face at the changed location; again the table is inclined in the same direction say by another 5 degrees to the next incremental position for welding; the electrode is readjusted to 1G position and welding process is carried out at the new location; this process is repeated many times over till the
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entire inner surface of elbow is welded and last bead partially overlaps the first bead to complete the process without changing the initial elbow set up, thereby covering all the four quadrants in one single set up.
The present invention is now described in the accompanying drawings. Fig.2 shows the front view and the top view of the invention. Fig. 3(a) shows start of welding and 3(f) shows the end of welding. The welding progress in different quadrants is shown in figs. 3(b), 3(c), 3(d) and 3(e).
Fig. 2 shows the front view and the top view of the invention comprising of a main frame (1). A table (2) is mounted on a shaft (3) to facilitate its rotation about X-X axis. The shaft is mounted on the main frame with the help of taper roller bearings for its rotation about X-X axis. The table is rotated about the X-X horizontal axis with the help of gearbox motor assembly (7). On this table the elbow (4) is secured by clamps (5) & (6) for overlay welding. The elbow rests on the bottom clamp (6) and is held firmly by using top clamp (5). The table rotates about the Y-Y axis with the help of a gearbox and motor assembly (8). A post (9) is positioned in the center hole of the table so that the same does not rotate about Y-Y axis when the table is rotated. The torch (10) used for welding the elbow is mounted on a curved member (11) in order to access the inside surface of the elbow, which in turn is mounted on support (12) which connects the curved member to the holder assembly (13). The holder assembly fits itself around the post firmly so that the curved member along with the torch is kept hanging inside the elbow for overlay welding of the inner surface.
Fig.3a, is a schematic drawing showing the start of the welding process inside the elbow starting from 0 degrees. The elbow (4) is securely clamped by clamps (5) and (6) on the table (2). The welding torch is set at 0 degrees and a welding run is done from one face of the elbow to the other face of the elbow by rotating the table about axis Y-Y. The table is then slightly inclined about axis X-X
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by the shaft say by 5 degrees is locked into the position. The welding electrode is then brought to 1G position and a welding run is done from one face to the other. Once again the table is slightly inclined, say by another 5 degrees in the same direction and is locked into the position as done earlier. Similarly, the welding electrode is again brought to 1G position for welding run from one face to the other. This process of welding and bringing the electrode to 1G position is repeatedly carried out till it reaches the position shown in Fig. 3(b).
Fig. 3(b) shows the welding runs completed till the table reaches the inclination angle of 45 degrees. The table is then slightly inclined about axis X-X by the shaft say by 5 degrees, beyond 45 degrees and is locked into the position. The welding electrode is then brought to 1G position and a welding run is done from one face to the other. Once again the table is slightly inclined, say by another 5 degrees in the same direction and is locked into the position as done earlier. Similarly, the welding electrode is again brought to 1G position for welding run from one face to the other. This process of welding and bringing the electrode to 1G position is repeatedly carried out till it reaches the position shown in Fig. 3(c).
Fig. 3(c) shows the welding runs completed till the table reaches the inclination angle of 90 degrees. The table is then slightly inclined about axis X-X by the shaft say by 5 degrees, beyond 90 degrees and is locked into the position. The welding electrode is then brought to 1G position and a welding run is done from one face to the other. Once again the table is slightly inclined, say by another 5 degrees in the same direction and is locked into the position as done earlier. Similarly, the welding electrode is again brought to 1G position for welding run from one face to the other. This process of welding and bringing the electrode to 1G position is repeatedly carried out till it reaches the position shown in Fig. 3(d).
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Fig. 3(d) shows the welding runs completed till the table reaches the inclination angle of 180 degrees. The table is then slightly inclined about axis X-X by the shaft say by 5 degrees, beyond 180 degrees and is locked into the position. The welding electrode is then brought to 1G position and a welding run is done from one face to the other. Once again the table is slightly inclined, say by another 5 degrees in the same direction and is locked into the position as done earlier. Similarly, the welding electrode is again brought to 1G position for welding run from one face to the other. This process of welding and bringing the electrode to 1G position is repeatedly carried out till it reaches the position shown in Fig. 3(e).
Fig. 3(e) shows the welding runs completed till the table reaches the inclination angle of 270 degrees. The table is then slightly inclined about axis X-X by the shaft say by 5 degrees, beyond 270 degrees and is locked into the position. The welding electrode is then brought to 1G position and a welding run is done from one face to the other. Once again the table is slightly inclined, say by another 5 degrees in the same direction and is locked into the position as done earlier. Similarly, the welding electrode is again brought to 1G position for welding run from one face to the other. This process of welding and bringing the electrode to 1G position is repeatedly carried out till it reaches the position shown in Fig. 3(f).
Fig 3(f) shows that inlay welding has been done on the entire inner surface of the elbow. Here it is observed that the last welding run is adjacent to the first welding run shown in fig. 3(a), effectively covering the entire expanse of the internal surface of the elbow without making any change in the %£ pp of the elbow right from the first quadrant to the fourth quadrant i.e. 0 degrees to 360 degrees.
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Advantages of the invention:
1. Considerable reduction in cycle time with number of setups reduced from four to one.
2. Repetitive set up for welding and change of fixture is avoided.
3. Welds are of the high quality since the entire welding is carried out in a single set up and the weld beads are exactly parallel to each other.
4. Productivity/quality is improved.
5. The overall operation is economized to a large extent.
9

WE CLAIM:
An improved turntable for overlay welding of elbows which comprises of a table mounted on a shaft which in turn is held between taper roller bearings fitted in a rigid frame for rotating the table about X-X axis from 0 degree to 360 degrees for overlay welding of entire inner surface covering all the four quadrants; as done conventionally, the table can also rotate from 0 degree to 360 degrees about axis Y-Y for welding the inner surface of the elbow from one face to another; the entire inner diameter (I.D) is covered by welded beads which partially overlaps the earlier bead; after each welding run the table is slightly inclined say by 5 degrees and the electrode is adjusted to 1G position i.e. perpendicular to ground and accordingly the welding process is carried out again from one face to another face at the changed location; again the table is inclined in the same direction say by another 5 degrees to the next incremental position for welding; the electrode is readjusted to 1G position and welding process is carried out at the new location; this process is repeated many times over till the entire inner surface of elbow is welded and last bead partially overlaps the first bead to complete the process without changing the initial elbow set up, thereby covering all the four quadrants in one single set up.
10

ABSTRACT:
The present invention relates to an overlay welding equipment to weld the entire inner surface of an elbow without changing the initial set up, covering all the four quadrants in one single set up. It provides a turntable which rotates around its vertical axis from 0° to 360° as available in conventionally method too. In addition, this turntable can also rotate 360° around the horizontal axis of the shaft on which it is mounted.
15 APR 2005
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Documents:

446-mum-2004-abstract (complete).doc

446-MUM-2004-ABSTRACT(15-4-2005).pdf

446-MUM-2004-ABSTRACT(GRANTED)-(20-7-2011).pdf

446-mum-2004-abstract.doc

446-mum-2004-abstract.pdf

446-MUM-2004-CANCELLED PAGES(4-7-2011).pdf

446-MUM-2004-CANCELLED PAGES(7-4-2010).pdf

446-mum-2004-claims (complete).doc

446-mum-2004-claims (complete).pdf

446-MUM-2004-CLAIMS(15-4-2005).pdf

446-MUM-2004-CLAIMS(AMENDED)-(4-7-2011).pdf

446-MUM-2004-CLAIMS(AMENDED)-(7-4-2010).pdf

446-MUM-2004-CLAIMS(GRANTED)-(20-7-2011).pdf

446-mum-2004-correspondance-received-140405.pdf

446-mum-2004-correspondance-received-230606.pdf

446-mum-2004-correspondance-received.pdf

446-MUM-2004-CORRESPONDENCE(15-4-2005).pdf

446-MUM-2004-CORRESPONDENCE(17-11-2008).pdf

446-MUM-2004-CORRESPONDENCE(21-09-2010).pdf

446-MUM-2004-CORRESPONDENCE(22-7-2011).pdf

446-MUM-2004-CORRESPONDENCE(6-8-2010).pdf

446-MUM-2004-CORRESPONDENCE(IPO)-(20-7-2011).pdf

446-mum-2004-correspondence(ipo)-(9-4-2009).pdf

446-mum-2004-description (provisional).pdf

446-MUM-2004-DESCRIPTION(COMPLETE)-(15-4-2005).pdf

446-MUM-2004-DESCRIPTION(GRANTED)-(20-7-2011).pdf

446-MUM-2004-DESCRIPTION(PROVISIONAL)-(15-4-2004).pdf

446-MUM-2004-DRAWING(15-4-2005).pdf

446-MUM-2004-DRAWING(22-7-2011).pdf

446-MUM-2004-DRAWING(7-4-2010).pdf

446-MUM-2004-DRAWING(AMENDED)-(7-4-2010).pdf

446-MUM-2004-DRAWING(GRANTED)-(20-7-2011).pdf

446-mum-2004-drawings.pdf

446-MUM-2004-FORM 1(15-4-2004).pdf

446-MUM-2004-FORM 1(4-7-2011).pdf

446-mum-2004-form 13(4-7-2011).pdf

446-MUM-2004-FORM 2(COMPLETE)-(15-4-2005).pdf

446-MUM-2004-FORM 2(GRANTED)-(20-7-2011).pdf

446-MUM-2004-FORM 2(PROVISIONAL)-(15-4-2004).pdf

446-MUM-2004-FORM 2(TITLE PAGE)-(4-7-2011).pdf

446-MUM-2004-FORM 2(TITLE PAGE)-(COMPLETE)-(15-4-2005).pdf

446-MUM-2004-FORM 2(TITLE PAGE)-(GRANTED)-(20-7-2011).pdf

446-MUM-2004-FORM 2(TITLE PAGE)-(PROVISIONAL)-(15-4-2004).pdf

446-MUM-2004-FORM 3(15-4-2005).pdf

446-MUM-2004-FORM 3(7-4-2010).pdf

446-MUM-2004-FORM 5(15-4-2005).pdf

446-mum-2004-form-1.pdf

446-mum-2004-form-18.pdf

446-mum-2004-form-2 (complete).doc

446-mum-2004-form-2 (complete).pdf

446-mum-2004-form-2 (provisional).doc

446-mum-2004-form-2 (provisional).pdf

446-mum-2004-form-26.pdf

446-mum-2004-form-3.pdf

446-mum-2004-form-5.pdf

446-MUM-2004-POWER OF AUTHORITY(15-4-2004).pdf

446-MUM-2004-REPLY TO EXAMINATION REPORT(4-7-2011).pdf

446-MUM-2004-REPLY TO EXAMINATION REPORT(7-4-2010).pdf

446-MUM-2004-REPLY TO FIRST EXAMINATION REPORT(7-4-2010).pdf

446-MUM-2004-SPECIFICATION(AMENDED)-(7-4-2010).pdf


Patent Number 248494
Indian Patent Application Number 446/MUM/2004
PG Journal Number 29/2011
Publication Date 22-Jul-2011
Grant Date 20-Jul-2011
Date of Filing 15-Apr-2004
Name of Patentee LARSEN & TOUBRO LIMITED
Applicant Address L & T House, Ballard Estste, Mumbai
Inventors:
# Inventor's Name Inventor's Address
1 SANSARE RAMAKANT DHONDU LARSAN & TOUBRO LIMITED, Heavy Engeineering Division, H-Shops, Powai Works, Saki Vihar Road, Powai, Mumbai-400 072,
PCT International Classification Number B23Q1/60
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA