Thursday, 3 July 2014

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Details of Universal Electrode Holder used in Welding, Cutting, lancing, Gouging & also in Cladding (Equipped with Plasma enhancing mode)

The article is based on the information provided by the Inventor, Prof. Sunil Pandey in  his application for patent.


"AN UNIVERSAL ELECTRODE HOLDER FOR SHIELDED METAL ARC WELDING"
The present invention discloses an universal electrode holder for shielded metal arc welding, the electrode holder comprising a body having two ends, and an electrode housing and plunger housing characterised in that said  electrode housing has an orifice provided with an end cap, a collet, an inlet for holding powder feeding means, and a powder feeding means, and plunger housing having an orifice being provided with a spring action means
and a plunger comprising a plunger head and a plunger rod, and an inlet for holding gas feeding means, and electrical connection means. [Fig. 1]

INVENTOR:
The present invention is by Dr. Sunil Pandey, Department of Mechanical Engineering,
Indian Institute of Technology Delhi (IITD), Hauz Khas, New Delhi -110016, India, an Indian National.


FIELD OF THE INVENTION :

The present invention relates to an electrode holder for welding, particularly to an electrode
holder for shielded metal arc welding, more particularly to an universal electrode holder for
shielded metal arc welding, even more particularly to an universal electrode holder for shielded metal arc welding and such processes and method of use thereof.


BACKGROUND OF THE INVENTION :

Welding is the most attractive fabrication technology in the world today and will remain
so even in the next millennium. The Shielded Metal Arc Welding (SMAW) process will
continue to dominate the welding scene and particularly in our country, where almost 
70% welding is still done using this process.


However, in a process of welding fabrication, a fabricator or welder is generally required

to do Lancing, Cutting and Surfacing apart from conventional shielded metal arc Welding.
The major limitation of the presently known electrode holders and of the processes of
use thereof, is that a fabricator or welder has to maintain large inventories of the equipment and/or consumables related to these processes.


Particularly, he is required to maintain inventory of various types of electrode holders 

related to these processes. These compulsions put a heavy financial pressure on
fabricator or welder, else he will have to be contented with whatever he can do with
the type of equipment available in the shop.


Further limitation of the presently known electrode holders and of the processes

of use thereof, is that for welding of thick plates the fabricator or welder has to go in for
more number of passes to weld it.


Such limitations put a heavy financial pressure on many fabricator or welder, which in turn

results in making the whole industrial process unaffordable. In order to overcome the problem of un-affordability the fabricator or welder will have to be contented with whatever he can do with one type of equipment, particularly electrode holder.


Still further limitation of the presently known electrode holders and of the processes of use thereof, is that the customer is also affected by these limitations and he is forced to search for those fabricators who have all the facilities to do a complete job. In the light of these limitations a small but enterprising person can't become a successful entrepreneur, as he can not meet the requirements or needs of the customers.



Yet another limitation of the known electrode holders and related processes is that

following operations can not be performed using one of the presently known holders
which employ solid covered electrode :
1. Deposit weld beads with reduced crown height
2. Deep penetration welding
3. Cutting
4. Lancing
5. Cladding
6. Surfacing and
7. Alloying etc.
The present inventor has found that these limitations can be overcome by making the
existing welding process flexible. This means the welder should be able to do lancing, cutting, surfacing, deep penetration welding and conventional shielded metal arc 
welding etc. with minimum inventory particularly by using one electrode holder. The present inventor has further found that the required flexibility will be achieved if the existing electrode holders can have provision for feeding :
1. Plasma forming gases to obtain deeper penetrations,
2 Oxygen during arcing to oxidise the metal to do cutting and lancing operation.
3. Powders during welding to do surfacing, cladding, etc.


NEED OF THE INVENTION :

Therefore, there is a need to develop a universally acceptable electrode holder and of the
process of use thereof, which would overcome some of the limitations of the presently known electrode holders and of the processes of use thereof as stated herein above. The particular need is to have an electrode holder which can universally perform above stated processes.


OBJECTS OF THE INVENTION :

This is the main object of the present invention to make a disclosure of a universally
acceptable electrode holder and of process of use thereof, which would overcome some of 
the limitations of the presently known such electrode holders and of such processes of use
thereof, as stated herein above.


This is further an object of the present invention to make a disclosure ox a electrode holder

and of the process of use thereof, having a flexibility of feeding a gas, like shielding or
cutting etc., and of a powder, like metallic or ceramic or combination of alloying elements 
etc. through a tubular covered electrode.


This is another an object of the present invention to propose for an electrode holder and 

of the process of use thereof, which will allow a complete flexibility to a fabricator or welder
to carry out welding, lancing, cutting, surfacing processes etc. employing the presently
disclosed electrode holder.


Further an object of the present invention is to have an electrode holder and of the process

of use thereof, which will have provision of holding a tubular covered electrode through which a gas or mixture of gasses or a powder or both - a gas and powder be fed to the weld pool.


Still another an object of the present invention is to make a disclosure of an electrode holder

which is provided with a provision for feeding a gas, which can be a shielding gas or gas for 
cutting & lancing operation.
Yet another an object of the present invention is to make a disclosure of an electrode holder
which is provided with a provision for feeding a powder, which can be metallic or ceramic or
a combination of alloying elements for surfacing purposes.
This is still another an object of the present invention to make a disclosure of an electrode
holder which is provided with a provision for feeding a gas or powder both through a tubular 
covered electrode which inturn can be fed to the weld pool.
Other objects and preferred embodiments of the.present invention will be more apparent from the following description when read in conjunction with the accompanying figure which is not intended to limit the scope of the present invention

BRIEF DESCRIPTION OF THE INVENTION :
According to the present invention an electrode holder for welding, particularly an electrode
holder for shielded metal arc welding, more particularly an universally acceptable electrode
holder for shielded metal arc welding, even more particularly an universal electrode holder
for shielded metal arc welding, which is universally acceptable not only in conventional 
welding but also suitable in carrying out special processes like lancing, cutting, surfacing, 
deep penetration welding etc. with minimum inventory, particularly with one electrode holder
only, more particularly with presently disclosed electrode holder only, wherein the said 
electrode holder, herein after referred to as "holder", comprises of a body having two end
and two parts, wherein one of the parts referred to as an electrode housing having an orifice
is provided with an end cap, a collet, an inlet for holding powder feeding means, and a
powder feeding means, and another part referred to as plunger housing having an orifice
is provided with a spring action means and a plunger comprising a plunger head and a
plunger rod, and an inlet for holding gas feeding means and a gas feeding means, and
electrical connection means.The preferred embodiments of the present invention will be more apparent when the following description is read in conjunction with the accompanying figure which is not intended to limit scope of the present invention.


DETAILED DESCRIPTION OF THE INVENTION :

Accordingly an electrode holder for welding, lancing, surfacing, cutting, deep penetration 
welding processes etc. is disclosed wherein said holder, comprises of a body 1 having two 
end referred to as 'left end' 2 and 'right end' 3 and two parts referred to as electrode housing 4 and plunger housing 5 characterised in that said electrode housing 4 having an orifice 6 is provided with an end cap 7 and a collet 8 to hold an etectrode, preferably an hollow electrode, more preferably a tubular covered electrode 9 having an orifice 10, and an inlet 11 for holding a powder feeding means and a powder feeding means 12, for feeding a powder, having a powder flow control means 13 to control flow rate of powder and an orifice 14 for flow of powder from said means 12 to said orifice 6 provided in said electrode housing 4, wherein said collet 8 sits in the orifice 6 provided in said electrode housing 4  towards left end 2 of the body 1 and said end cap 7 is fitted onto said electrode housing 4 towards left end 2 of the body 1 after placing collet 8 in the orifice 6. The collet 8 is also provided with an orifice 15 which aligns with orifice 6 provided in electrode housing 4 and orifice 10 provided in electrode 9.
The another part referred to as plunger housing 5 having an orifice 16 is provided with a spring
action means 17 and a plunger 18 comprising a plunger head 19 and a plunger rod 20, and
an inlet 21 for holding gas feeding means and a gas feeding means 22 and electrical
connection means 23, wherein said spring action means 17 is helical spring 17, said plunger
head 19 sits in orifice 16 towards left end 2 of the body 1 to close orifice 6 when gas flow is
not required, and plunger rod 20, provided with an longitudinal groove 24 and a gas flow 
control means 25, sits in orifice 16 towards right end 3 of the body 1 and projects out of the
opening 26 of the plunger housing 5 and such opening 26 is a continuous part of the orifice
16. The projected end of the plunger rod 20 is provided with a gas flow control means 25
consisting of a control knob 25 fitted onto plunger rod 20. The control knob 25 alongwith
spring action means 17 makes the said plunger 18 movable in left and
right directions to allow and close the flow of gas through orifice 6 provided in electrode
housing 4.
In accordance to the preferred embodiment of the present invention the plunger head 19 and plunger rod 20 are preferably continuous parts of plunger 18, that is these parts (19 and 20)  are preferably made form a single piece of selected material. However, two separate parts can be joined together by any known means. An 'O' ring 27 or a gas sealing means is provided in the central part 28 of the plunger 18 to provide gas sealing. The 'O' ring 27 sits in a groove (not visible in the figure due to sitting of 'O' ring 27) provided onto central part 28 of the plunger 
18 and stops flow of gas towards right end 3 of the body 1. In accordance to preferred
embodiment of the present invention the spring action means 17 fits on the plunger rod 20 
and sits towards the central part 28 of the plunger 13.
In accordance to one of the preferred embodiments of the present invention the projecting part of the plunger rod 20 is provided with threads for better fitting in the opening 26 of the plunger housing 5 and to hold the gas flow control knob 25 and the part supporting the spring action means 17 is non-threaded.
In accordance to preferred embodiment of this invention the gas feeding means 22 consisting  a gas inlet nipple 22 having an orifice 26 to allow the flow of gas are provided towards left end 2 of the body 1. The gas feeding means 22 preferably provided with male threads sit in respective inlet 21 which inturn is preferably provided with female threads to hold the gas feeding means 22.
In accordance to one of the preferred embodiments of this invention plunger housing 5 is
fitted onto electrode housing 4 by known means preferably by threading mechanism or 
by push on mechanism, more preferably by threading mechanism. However, a single piece
body 1 comprising electrode housing 4 and plunger housing 5 can also be used. The 
advantage of two piece body 1 is to have ease of fabrication of the device, because the
orifice 6 and orifice 16 are of varying diameters. The orifice 6 has lower diameter in the
central part and higher diameter towards opposite ends. The diameter towards said left 
end 2 is to suit the dimensions of collet 8 and diameter towards right end 3 of the body 1
is to suit diameter of the plunger head 19 part of which sits in it (6). The orifice 16 has higher  diameter towards left end 2 of the body 1 to fit onto electrode housing 4 and lower diameter in the central part to house central part 28 of the plunger 18 and further lower diameter at an opening 26 to ho!d plunger rod 20.
The electrical means 23 are as known in the art, preferably these comprises of insulated
handle 23 fixed onto plunger housing 5 of the body 1 by any known means preferably by
mounting nut 29 having threads for tightening of the handle 23 through tightening means 30.The power cable is attached to the handle 23 at an end 31 opposite to the body 1 by means  of cable tightening screws 32.
The body of the presently disclosed holder is preferably made from Brass. However, other 
conducting alloys which can retain shape and are lightweight can also be used. 
In accordance to one of the preferred embodiments the flow of the powder is maintained perpendicular to take full advantage of gravity for feeding powders through a tubular electrode while performing the down-hand, vertical-down, flat or horizontal arc welding. To ensure the positive feeding, the powder is made to flow through a venturi.
In accordance to one of the preferred embodiments the powder can be any preferably 
metallic or ceramic or combination of alloying elements and the gas can be any gas known or used in the art for welding, lancing, surfacing, cutting processes etc.In accordance to the preferred embodiment of this invention orifice 6 provided in electrode housing 4, orifice 10 of the tubular covered electrode 9, orifice 14 provided in powder feeding means 12, orifice 16 provided in plunger housing 5 orifice 26 provided in gas feeding means 22 align with each other allow mixing of the gas and/or powder in weld pool.The presently disclosed electrode holder is flexible and in combination with tubular covered electrode allows the following major advantages over existing shielded metal arc welding electrode holders and their respective processes :
1. Conventional SMAW: Conventional SMAW can be performed in the following ways:
a) Using commercially available solid covered electrodes.
b) Using hollow / tubular covered electrodes.


2. Deep penetration SMAW: Deeper weld penetrations are obtained when a plasma

forming gas is fed through the orifice of the tubular electrode during welding. This
advantage is not possible with the conventional process. The weld beads made with this 
process will have reduced crown height and angle of convexity due to high centre line 
velocity, which accelerates the detached droplets towards the weld pool. Reduced metal deposition rate also ensures better load carrying capacity.
Orifice gases such as argon, helium, carbon dioxide or mixtures of gases will form fully
ionised plasma at the tip of the tubular electrode. This increases the heat of the arc and 
coupled with high centre line velocity, which accelerates the detached droplets, results in
deeper penetration. The penetrations observed during the tests were 2~3 times more than the conventional arc welding.
The process may be suitable for pipe welding in place of celiulosic electrodes for higher
penetration.
3. Oxy-Arc Cutting: Rapid oxidation takes place when oxygen is fed through an orifice of
the tubular electrode. The oxygen fed at high pressure partly forms the plasma and the 
remaining oxygen is used in oxygen process. This is a smooth fast clean cutting operation
at very low currents. This is not possible with the conventional SMAW process.


4 Oxy-Arc Lancing: The oxygen, when fed at high pressure through the tubular electrode 

cause a very rapid oxidation. In this mode the process is used for lancing. This gives 
smooth fast clean lancing operation without any limitations of the conventional oxygen lancing. Preheating is done by establishing the arc and it's heat.


5. Surfacing /-coating: When powders are fed through the orifice, the process can be used 

for surfacing, cladding and buttering at very low cost. The present invention has been described with the help of the accompanying figure which is not intended to limit scope
of the invention. It is obvious to those working in the art that various modifications are possible without deviating from scope of the present invention.


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