|Title of Invention||
A FIXTURE FOR PETAL TO PETAL WELDING OF DISHED ENDS USING SAW PROCESS
|Abstract||"A fixture for petal to petal welding of dished ends using saw process" comprises of two rings (5), which are split into two halves; the two ring halves (5) are interconnected using the pipe sections (2) to give rigidity to the structure; at the horizontal split line of the ring assemblies (7)' four blow-holes each are provided to clamp the rings (5) against each other to complete a circle; the said rings are provided with the clamping bolts on the inner side; the bolts project from the clamps (8) and tighten on the dished end outer surface. Dated this 24th December 2004|
|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
."A fixture for petal to petal welding of dished ends using saw process"
(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
The following: invention,.
The following specification particularly describes the invention and the manner in which it is to be performed.
21 FEB 2008
Present invention relates to the hemispherical dished end welding fixture. More particularly present invention relates to the fixture used for welding the hemispherical dished end petal-to-petal long seams with the process of submerged arc welding (SAW).
In prior art practice of welding the long seams of hemispherical dished ends is by following methods:-
1. Shielded Metal Arc Welding (SMAW) for welding the first side as well as the chip back side.
2. Submerged Arc Welding (SAW) for welding the first side while the dished end is mounted on the Aranson positioneer and then chip backside welding by SMAW.
In the existing methods 0f welding only one Dished End is processed at a time.
The welding process of SMAW is 10 times lower in productivity than SAW hence
consumes more cycle time. As per the existing practice, welding of the dished ends with SAW requires Aranson positioner, which is a heavy capital investment.
The fixture according to the present invention is made by modifying the existing rings made for supporting the heavy thin walled cylindrical vessels during rotation.
The fixture is made in two rings, which are split into two halves. The two ring halves are interconnected using the pipe sections to give rigidity to the structure. At the horizontal split line of the ring assemblies' four blow-holes each are provided to clamp the rings against each other to complete a circle. The said rings are provided with the clamping bolts on the inner side. The bolts project from the clamps and tighten on the dished end outer surface.
The present invention, therefore, comprises of a fixture which consists of two rings which are split into two halves, the two ring halves being interconnected using pipe sections giving rigidity to the structure, at the horizontal split line of the ring assemblies
four blow holes are provided to clamp the rings against each other to complete a circle, the said rings being further provided with the clamping bolts on the inner side, these bolts project from the clamps and tighten on the dished end outer surface.
The preparation of dishes end for welding with the fixture involves the following activities:
1. The petal-to-petal long seam set up of the individual hemispherical dished end is completed in all respect.
2. One of the dished end is placed on the ground with the trimming line marked on the open-end water leveled.
3. The support elements connecting the two dished ends are set up and welded on the inside of the above dished ends. Welding is done on the excess portion, which will be trimmed off after welding.
4. The second dished end is placed above the same with its long seams matching with the earlier one.
5. The support elements placed earlier are now welded to this dished end inside.
The dished ends making a sphere is now ready for assembly with the fixture.
The assembly of the above sphere in the fixture is done in the following sequence.
1. The lower half of the fixture is placed on the ground or tank rotators with the horizontal flange facing up while the same is supported to remain rigid.
2. The clamping bolts in the lower half are raised to support the job from bottom depending on the radius of the same.
3. Sphere made by connecting the two dished ends is placed on the above fixture while maintaining the set of four seams in a single plane along the centerline of the two rings.
4. The top half of the fixture is placed above and clamped at the horizontal flange.
5. Clamping bolts in the upper half are tightened against the dished end surface to rigidly held the same inside the fixture.
The above assembly is placed on the tank rotators and rotated to weld the long seams.
After completing outside welding of the set of 4 seams, fixture is rotated on tank rotators to get the trimming lines parallel to the ground. Supports are connected to the fixture are loosened and the sphere is rotated inside to get a new set of seams for welding.
The SAW machine head is taken inside from the space at the center while the machine is placed perpendicular to the plane of the four seams. A platform form the opposite side provides a seat for the welder and welding is done by rotating the sphere on the tank rotators.
After completion of all the welding, removing the bolts connecting the two flanges separates the upper half of fixture. Cutting off the supports connecting the two separates the hemispheres.
The invention will now be described with the help of suitable drawings accompanying this specification wherein the salient features have been shown by suitable numerals and referred to appropriately in the following description :
Drawing comprises 3 figures.
Fig.l shows the sketch of the fixture having two hemispheres set up and connected to form a sphere.
Fig.2 shows the hemispheres set up and ready for welding.
Fig.3 shows the hemisphere positioned on tank rotators for welding.
Referring to fig. 1, numeral 1 shows the top hemisphere maintaining the trimming lines parallel, numeral 2 shows hemisphere connectivity members and numeral 3, shows bottom hemisphere placed with the trimming line leveled.
Referring to fig.2, numeral 4 shows saw machine, numeral 5 shows fixture rings, numeral 6 shows seam to weld, numeral 7 shows ring connecting members and numeral 8 shows clamp.
Referring to fig.3, numeral 5 shows fixture rings and numeral 8 shows clamp.
Advantages of the invention :
The fixture made the welding of the hemispherical dished end's possible by the most productive method of SAW reducing the cycle time in manufacturing.
The fixture saved cost of manufacture since the same were modified from the existing set of rings available.
l."A fixture for petal to petal welding of dished ends using saw process" comprises of two rings (5), which are split into two halves; the two ring halves (5) are interconnected using the pipe sections (2) to give rigidity to the structure; at the horizontal split line of the ring assemblies (7)' four blow-holes each are provided to clamp the rings (5) against each other to complete a circle; the said rings are provided with the clamping bolts on the inner side; the bolts project from the clamps (8) and tighten on the dished end outer surface.
Dated this 24th December 2004
|Indian Patent Application Number||1223/MUM/2003|
|PG Journal Number||40/2008|
|Date of Filing||27-Nov-2003|
|Name of Patentee||LARSEN & TOUBRO LIMITED|
|Applicant Address||L&T HOUSE, BALLARD ESTATE, MUMBAI,|
|PCT International Classification Number||B23K9/18|
|PCT International Application Number||N/A|
|PCT International Filing date|