FIELD OF INVENTION
The invention generally relates to an apparatus and process for deep bore
stelliting of valve components. More particularly, the invention relates to a sleek
gas cooled MIG welding torch capable of carrying out welding inside the deep
bores in valve components. The invention further relates to a device for
accurately positioning the torch inside the deep bores with repetiting accuracy to
achieve a consistently good quality of stellite welds.
BACKGROUND OF THE INVENTION
A few specific type of valve bodies requires stellite deposition on its seating area
which is located inside a deep bore. Thus, the method of stellite deposition in
such valve components becomes very difficult due to the inaccessibility of the
groove location and almost no-visibility of the weld pool by the operator during
welding process. These disadvantages of the job discounts a manual welding for
the process of MIG welding inside the narrow and deep bores in valve
components. Thus, only mechanized welding could be employed for such
requirements. TIG or MIG welding process is normally employed for depositing
stellite in such valve components. Conventional TIG and MIG torches are
normally larger in diameter and hence cannot be used for welding in deep bores.
The goose-necked MIG torches cannot enter the narrow bore due to the large
bend angle. The straight-necked MIG torch can although be inserted into the
bore, but the fouls torch at the mouth of the bore when it is tilted to access the
groove. Accordingly, the state of art warrants development of a sleek torch with
proper bend angle for welding inside such narrow and deep bore. Also different
bore diameter and groove location depth requires different sizes of special torch
to suit each of the bore sizes. Further, an act of manually inserting the MIG welding torch into the narrow bore,
and then positioning the welding wire accurately into the groove located deep
inside the narrow bore, is indeed a difficult task. Any deviation in the wire position
with respect to the groove would result in groove edge burning and would spoil
the weld.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a sleek gas cooled MIG
welding torch capable of carrying out welding inside the deep bores in valve
components, which eliminates the disadvantages of prior art.
Another object of the invention is to propose a sleek gas cooled MIG welding
torch having a bend angle for allowing an easy access into the deep bore of a
valve component and deposit stellite by MIG welding process, which eliminates
the disadvantages of prior art.
A still another object of the invention is to propose a sleek gas cooled MIG
welding torch provided with a torch positioning device which accurately positions
the torch with respect to the groove located inside the deep bore .
.A further object of the invention is to propose an improved deep bore stelliting
system for depositing stellite weld metal inside a narrow and deep bore of a valve
body.
A still further object of the invention is to propose a shielding gas mixture of
80%C02+20%Argon adaptable by an improved deep bore stelliting system for
welding with metal cored stellite wire. These and other objects and advantages of the invention will be apparent from
the ensuing description.
At the outset of the description, which follows, it is to be understood that the
ensuing description only illustrates a particular form of this invention. However,
such a particular form is only an exemplary embodiment and the teachings of the
invention are not intended to be taken restrictively.
SUMMARY OF THE INVENTION
Accordingly, there is provided a sleek MIG welding torch configured mountable
on a column and boom type torch positioning system for allowing an easy access
into narrow and deep bore of a valve component. The SIT process with metal
cored wire and 800/0C02 and 20%Argon shielding gas mixture provide an
improved weld quality and productivity in deep bore stelliting involved in valve
components.
In order to eliminate the prior art problems, the present invention provides a
column and boom type torch positioning system equipped with calibrated scales
for monitoring the horizontal and vertical movement of the torch has been
developed to enable easy and accurate positioning of the torch into the groove.
According to the invention, an irregular shaped valve body with narrow and deep
bore is held in a chuck mounted on a rotating positioner using a specially
designed fixture to properly receive the torch into the groove and rotate the job
at a preset speed during welding.
The mechanized torch positioning system equipped with the sleek MIG welding
torch in combination with the job holding, and a rotating positioner enables an
easier stelliting in deep bore . Thus, the inventive SIT MIG welding process
provides a better satellite weld metal quality as compared to the conventional
MIG welding. In this regard, the deep bore stelliting system of the invention overcomes the
limitations of prior art described hereinabove. The improved deep bore stelliting
system provides a better stellite weld quality and productivity in the valve
components and similar other applications.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1- Shows an embodiment of the improved MIG welding torch according to
the invention.
Figure. 2- shows an embodiment of a torch positioning system adaptable to the
improved MIG welding torch according to the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
Referring now to the drawings wherein like reference numerals designate
identical or corresponding parts throughout the several views. Fig 1 shows a
sleek MIG welding torch (11) which allows an easy access into the narrow and
deep bore in the valve body. In this torch (11). an adapter (1) is designed to fit
directly into the torch holder. A main frame (2) of the torch (11) is insulated and
carries the welding current and also guides a metal cored type electrode wire
required for the welding. A contact tip adapter (3) fits into a curved end of the
torch body (2) and holds a contact tip (4). An insulated outer nozzle (5) guides a
shielding gas. Fig 2 shows the schematic diagram of a torch positioning system (TPS). In the
system, a bed plate (6) supports a column (7) including a motorized boom (8). A
vertical slide (9) is driven by an electric motor (10) is used to insert and locate the
sleek torch (11) inside the narrow and deep bore in the valve body (14) which is
held in a rotating positioner (12) which is mounted on a support structure (13).
The rotating positioner has a means for tilting the job by required degrees. The
rotational speed including forward and reverse direction change is regulated
through a controller during welding.
The SIT MIG welding process with a composition of 80%C02 +20%Argon is
established for the deep bore stellite cladding in valve manufacture according to
the invention. The new shielding gas composition avoids spatter and gives
smooth weld deposit with good fusion.
The advantages of the invention can be seen, inter alia, in the fact that the lathe
type rotating fixture for welding of bifurcates produces improved weld quality and
productivity.
WE CLAIM
1. An improved deep bore stelliting system for depositing stellite weld metal
inside a narrow and deep bore of a valve body, the system comprising:
an insulated gas cooled sleek MIG welding torch (11) carrying a
welding current, a shielding gas, and a wire for welding inside a
narrow and deep bore in valve components;
a remote pendent operated mechanized torch positioning system
(TPS) enabled to move vertically and/or horizontally, and capable
of positioning the torch (11) accurately into a groove located inside
a deep bore of the valve body; and
a shielding gas mixture comprising 800/0C02 +200/0Argon for stellite
welding using a metal cored stellite wire.
2. An improved deep bore stelliting system as claimed in claim 1, wherein
the sleek MIG welding torch comprises:_
-an adapter (1) configured to directly fit into the torch holder;
-a main frame (2) which carries the welding current and guides an
electrode wire; and
-a contact tip (4) accommodated in a tip adapter (3) which is configured to
releasably attach to a curve end of the torch frame (2) 3. An improved deep bore stelliting system as claimed in claim 1, wherein
the torch positioning system (TPS) comprising:
a base plate (6) supporting a coloumn (7) and a motorized boom
(8);
a vertical slide (9) driven by an electric motor (10) which allows the
sleek torch (11) an insertion and positioning inside the narrow and
deep groove in the valve body (14), the valve body (14) being held
on a rotating positioner (12) which is mounted on a support
structure (13).
4. An improved deep bore stelliting system as claimed in claim 1, comprising
a controller to regulate the rotational speed of the torch including its
forward and reverse movement according to the process parameters.
5. A shielding gas mixture for carrying out a method of deep bore stelling of
valve components in an improved system as claimed in any of claims 1 to
4, comprising 80% C02 + 20% Argon, and wherein the method adapts a
metal cored stellite wire.
6. An improved deep bore stelliting system for depositing stellite weld metal
inside a narrow and deep bore of a valve body, as substantially described
and illustrated herein with reference to the accompanying drawings.