FIELD OF INVENTION
The invention generally relates to drum shaft of draw works of oil rigs. More
particularly, the invention relates to an improved method and device for insertion
of a drum shaft into a drum to form a defect free drum shaft assembly.
BACKGROUND OF INVENTION
Basicconstructional feature of a Drum Shaft assembly is as follows:
a) a Drum
b) a Drum Shaft
Subsequent to the machining of the above two items to a reqUired dimension,
they are unitized by interference fit to avoid any slippage between the drum and
the drum shaft while transmitting the huge torque.
In prior art process of Drum shaft insertion into drum, a high capacity for
example, 200 tons Hydraulic Pressis used in horizontal direction.
This assembly procedure has the following disadvantages:
1) This assembly procedure is a force-fit technique and carried-out at
ambient temperature.
2) The process is time consuming and generally results in tearing of the
drum shaft surface.
3) Since the assembly is done in horizontal position, the overhang of the
lengthy drum shaft of approx 3000mm, which is inserted in a drum of
length 2000m, a sag is generally developed dUring the assembly.
4) Sagging of the drum shaft leads to seizing and rubbing of the drum shaft
with the drum during insertion.
S) There are cases when the drum shaft gets jammed in the Drum before
completion of the full insertion, resulting in rejection of the total drum
shaft assembly.
OBJECTS OF INVENnON
It is therefore, an object of the present invention to propose an improved
processfor safe and easy insertion of a drum shaft into a drum to form a defectfree
drum shaft assembly.
Another object of the present invention is to propose an improved process for
safe and easy insertion of a drum shaft into a drum to form a defect-free drum
shaft assembly, in which the drum shaft dUring insertion into the drum does not
get jammed till the full insertion.
A further object of the present invention is to propose an improved process for
safe and easy insertion of a drum shaft into a drum to form a defect-free drum
shaft assembly, in which the total cycle time for the insertion is reduced.
A still further object of the invention is to propose a device for cooling the drum
shaft upto a cryogenic temperature before insertion into the drum.
SUMMARY OF INVENTION
Accordingly, there is prOVidedan improved method and a device for easy and
safe insertion of a drum shaft in a drum to form a defect-free drum shaft
assembly.
The method comprises:
- vertically positioning a drum for vertical insertion of a drum shaft
thereinto;
. cooling the drum shaft to a cryogenic temperature in an insulated Shrink
Fitting device by using liquid nitrogen;
- lifting the drum shaft vertically up, with an EOT Crane after sufficient
cooling of the drum shaft, the Keys fixed on the drum shaft are aligned
with the Keyways in the Drum;
- aligning a plurality of keys affixed to the drum shaft with a corresponding
number of keyways configured in the drum; - gradually lowering the drum shaft:with the EOTcrane such that the drum
shaft:slides into the drum without any metal to metal contact till the collar
configured on the drum shaft:butts with the hub provided on the drum.
This process of insertion helps to improve the joint efficiency and also
eliminates any remote possibility of jamming or damage.
BRIEf DESCRIPTION Of THE ACCOMPANYING DRAWINGS:
Figure-1- shows a drum of an oil rig.
Figure-2- shows a drum shaft which forms a drum shaft assembly with the drum
of Fi.g.l.
Figure-3- shows a drum shaft assembly after insertion of the drum shaft into the
drum.
Figure-4 shows a device adapted to cool the drum shaft up to a cryogenic
temperature before insertion into the drum according to the invention.
DETAIL DESCRIPTION OF THE INVENTION
Fig. 1 shows a drum (1) for accommodating a drum (2) of an oil rig having an
annular space(la) to insert the drum (2).
Fig. 2 shows the drum (2) of an oil rig.
Fig. 3- shows as assembly of the drum (1) and the drum shaft (2) after insertion
of the drum shaft (2) into the annular space (la) of the drum (1).
Fig. 4- shows a device (3) for cooling the drum shaft (2) upto cryogenic
temperature by inputting nitrogen gas into the device after placing the drum
shaft (2) into the device (3). The drum shaft (2) is inserted vertically into the
drum (1) by using an EDT-crane. The drum shaft (2) is configured with a
plurality of keys, which have corresponding keyways designed onto the drum (1).
Alignment and insertion of the drum shaft (2) into the drum (2) is arranged by
.
using the EDT-crane, after the drum shaft (2) is cooled to a cryogenic
temperature. This enables an insertion of the drum shaft (2) into the drum (1)
without a metal to metal contact, and with ease to avoid any half-way jamming
of the drum shaft (2) during insertion into the drum. The invention thus allows
forming a defect-free drum shaft assembly.
We Claim:
1. An improved method for easy and safe insertion of a drum shaft of an oil
rig into an annular space configured into a drum to form a defect free
drum shaft assembly, the method comprising the steps of:
- vertically positioning the drum for vertical insertion of a drum shaft
thereinto;
- cooling the drum shaft to a cryogenic temperature in an insulated Shrink
Fitting device by using liquid nitrogen;
- lifting the drum shaft vertically up, with an EDT Crane after sufficient
cooling of the drum shaft, the Keys fixed on the drum shaft are aligned
with the Keyways in the Drum;
- aligning a plurality of keys affixed to the drum shaft with a corresponding
number of keyways configured in the drum;
- gradually lowering the drum sh~ft with the EDT crane such that the drum
shaft slides into the drum without any metal to metal contact till the collar
configured on the drum shaft butts with the hub proVidedon the drum.
2. A device for cooling a drum shaft upto a cryogenic temperature for easy
and safe insertion of a drum shaft of an oil rig into an annular space
configured into a drum to form a defect-free drum shaft assembly, the
device comprising:
-a housing designed with one each closeable openings on the top and
on the side of the housing, the housing haVing a size so as to vertically
accommodate the drum shaft (2) With suitable tolerance;
; -the top opening allowing placement of the drum shaft (2) by an EOT
crane, and on completion of a cryogenic cooling of the drum shaft
allowing ingress of the shaft (2), the top opening being tightly closeable
during the step of cryogenic cooling; and
-the side opening allOWing supply of nitrogen gas inside the device
housing for cooling, the side opening being closeable during the cooling.
3. An improved method for easy and safe insertion of a drum shaft of an oil
rig into an annular space configured into a drum to form a defect free
drum shaft assembly, as substantially described and illustrated herein with
reference to the accompanyingdrawings.
4. A device for cooling a drum shaft upto a cryogenic temperature for easy
and safe insertion of a drum shaft of an oil rig into an annular space
configured into a drum to form a defect-free drum shaft assembly, as
substantially described and illustrated herein with reference to the
ac;companyingdrawings.