Development of electric weeding torch with casing on one end to form inert gas shiel

Allen, G. V.

English

NASA Technical Reports Server

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
WASHINGTON, D.C. 20546 
REPLY TO 
A R N  OF: G P  April 5, 1971 
MEMORANDUM 
~ ~ I / S c i e n t i f i c  & Technical Information Division % 
Attn: M ~ S S  Winnie M. Morgan 
FROM :  office of Assistant  General 
Counsel f o r  Patent Matters 
SUBJECT : Announcement of NASA-Owned 
U.S. Patents i n  STAR 
I n  accordance with the procedures contained i n  the Code GP 
t o  Code US1 memorandum on t h i s  subject ,  dated June 8, 1970, 
the  attached NASA-owned U.S. patent is  being forwarded f o r  
abstract ing and announcement i n  NASA STAR. 
The following information is provided: 
U.S. Patent No. 
Corporate Source : Marshall Space Fl ight  Center  
Supplementary 
Corporate Source 
NASA Patent Case No.: m - 0 2 3 3 0  
~ a ~ l e  Parker 
Enclosure : - 
Copy of Patent 
( A C C E S S I O ~ E R )  (THRU) 
- 
OR TMX OR AD NUMBER) (CATEGORY) (NASA CR 
https://ntrs.nasa.gov/search.jsp?R=19710014322 2020-03-17T03:05:10+00:00Z
Spt .  23, 1969 
Filed Jan. 12, 1967 
G. V. ALLEN 
ELECTRIC WELDING TORCH 
3,469,069 
3 Sheets-Sheet 1 
i I 1 
FIG. I 
l N VEN TOR 
BY 
ATTORNEY 
hpt .  23, 1969 G. V. ALLEN 3,469,069 
ELECTRIC WELDING TORCH 
Filed Jan. 12, 1967 3 Sheets-Sheet 2 
ATTORNEYS 
Sept. 23, 1969 
Fi led  Jan. 12, 1967 
6. V. ALLEN 
ELECTRIC WELDING TORCH 
FIG. 4 A  
3,469,069 
3 Sheets-Sheet 3 
F I G .  4 C  
FIG. 48 FIG. 40 
INVENTOR 
GILBERT V. ALLEN 
ATTORNEY 
3,469,069 United States Patent Ofice 
,a,n, ,ep, ,, ,, 
3,469,069 
ELECTRIC WELDING TORCH 
Gilbert V. Allen, Athens, Ala., assignor to the United 
States of America as represented by the Administrator 
of the National Aeronautics and Space Administration 
Filed Jan. 12, 1967, Ser. No. 608,944 
Int. C1. B23k 9/12,9/16 
U.S. Cl. 219-130 3 Claims 
ABSTRACT OF THE DISCLOSURE 
not critical in that during the welding operation the area 
adjacent the weld becomes ionized and forms a current 
path from electrode to filler rod to workpiece. Penetration 
through an interface is achieved with the present invention 
5 by a driving or gauging action of the filler rod, whereas 
with conventional systems previously mentioned, such 
action could be achieved only by using very high currents. 
This action essentially cleans out the interface, it being a 
source of contaminating oxides and atmospheric gases, 
10 and the crater is filled from the center with clean filler 
metal to result in better fusion at the interface and thus a 
An electric welding apparatus that includes a welding 
head having a cylindrical casing at one end thereof that 
forms an inert gas shield. A fixed electrode is mounted in 
a canted and offset position in the casing by means of a 1 
conductive collar mounted to the interior surface of the 
casing. Filler wire from a feeder mechanism is fed through 
the center of the welding head to a weld puddle. Cooling 
water and inert shielding gases are routed to the weld 
better quality weld. 
It is therefore an object of this invention to provide an 
improved welding apparatus capable of consistently pro- 
(5 ducing quality spot welds. 
A further object of the present invention is to provide 
a welding device employing a center fed filler rod and an 
offset electrode. 
Other objects and attendant advantages of the invention 
area through conduits in the welding head. 20 will become more apparent when considering the follow- 
ing detailed description in conjunction with the attached 
drawings wherein: 
The invention described herein was made by an em- F I G ~ ~ R E  1 is-; perspective view of a welding device in 
ployee of the United States Government and may be position for spot welding; 
manufactured and used by or for the Government for 25 FIGURE 2 is an elevation view, partially cross-sec- 
governmental purposes without the payment of any tioned, of a welding device constructed in accordance with 
royalties thereon or therefor. the invention; 
This invention relates in general to welding devices. FIGURE 3 is a view in cross-section taken along lines 
More particularly this invention relates to a welding de- 3-3 of FIGURE 2; 
vice featuring an offset canted electrode and a center fed 30 FIGURES 4A through 4D are a schematic illustration 
filler rod that permits feeding of the filler rod directly of a spot welding sequence using the invention. 
into the center of a weld puddle. Referring to FIGURE 1 of the drawings, a welding de- 
The aerospace industry requires quality spot welding vice is shown in position over a workpiece 2 to be spot- 
techniques that produce spot welds which conform to rigid welded. The welding device includes a welding head 3 
specifications and can be consistently reproduced without 35 having a filler wire feeding mechanism 4 mounted on the 
depending upon the skill of an operator. Investigations upper end thereof and an inert gas shield 5 attached to 
have revealed spot welding techniques to be the most the other end thereof. The gas shield has notches 6 formed 
satisfactory method of joining miscellaneous small compo- on the lower end thereof which permits the area enclosed 
nent parts to large bulkheads and cylindrical skin sections by the shield to be purged of air by the inert gas supplied 
of space vehicles. However, spot welding techniques and 40 to the interior of the shield. The inert gas is supplied to 
devices previously available have not been adequate to the weld area via gas line 7 connected to the welding 
consistently produce welds of the required quality. For head and internal passageways, discussed hereafter, pro- 
example, resistance spot welding techniques are unsatis- vided in the welding device. Combined power and water 
factory due to physical limitations of size and non-port- outlet line 8 and water input line 9 are connected to the 
ability of the equipment. Further, in welding apparatus 4.5 welding device to provide electrical power and cooling 
available heretofore the filler rod used in such apparatus water thereto. The workpiece is illustrated herein as two 
has been mounted in a canted position so as to cause the plates being spot welded together; however, the workpiece 
weld puddle to spill over the sides of a weld crater as it is could take other forms. 
being filled with filler rod, giving rise to nonsymmetrical Referring now to FIGURES 2 and 3 of the drawing, 
and inconsistent spot welds. Irregular welds were inherent there is illustrated a sectional view of a welding head 
in the above filler rod arrangement in that the weld crater that includes a circular outer housing 12 of con~position 
is fed from one side which causes that one side of the material having a concentric copper tube 14 mounted 
spot weld to be higher than the other. aectrodes, too, therein. Tube 14 includes threaded surfaces 16 and 18 
were centrally mounted and often contaminated by the that extend below outer housing 12. A shield adapter 20 
puddle and filler rod due to excursions made by the elec- 55 mounted on tube 14 includes a threaded portion 22 that 
trode into the weld crater. threadably engages threaded portion 16; formed on tube 
The present invention avoids these difficulties by em- 14. A second copper tube or sleeve 24 is positioned within 
ploying an offset canted electrode and by center feeding a copper tube 14. Copper sleeve 24 has a plurality of 
filler rod through the central portion of the welding device threaded portions 25 formed thereon that engage threaded 
directly into the center of the weld area. The weld crater 60 portion 18 of tube 14 when copper tube 24 is inserted 
is filled more evenly and results in a spot weld having im- therein. Copper sleeve 14 has longitudinal grooves 26 and 
proved characteristics in that weld nugget diameters are 28 (see FIGURE 2) milled therein to form water passage- 
consistent and the exposed surfaces thereof are smooth ways through which cooling water is circulated to  remove 
and regular. Further, electrode contamination is elimi- heat generated during a welding operation. 
nated by the present invention since the electrode is fixed 65 Referring again to  FIGURE 2, it will be seen that tube 
and never penetrates the weld puddle as was the case in 24 has an enlarged portion 28 formed near the lower 
prior devices incorporating variable position electrodes end thereof. Enlarged portion 28 has a circular channel 
and canted filler rod positioning. 30 formed therein and also a shoulder 32 that abuts 
The offset canted position of the electrode employed 70 against a sealing surface or shoulder 34 formed on inert 
in this invention allows the arc to strike the area of the gas shield 5. Channel 301 forms a passageway in com- 
metal to be u7elded to form a crater. Electrode height is munication with slots or grooves 26 and 28 formed in 
3,469,069 
3 4 
copper tube 14 and thus provides a path through which new and novel welding apparatus has been disclosed that 
cooling water can be circulated. Normally an appropriate is capable of making improved welds. It  is also apparent 
seal will be positioned between shoulders 32 and 34 to that there will be many changes and modifications which 
prevent the escape of cooling water into the welding area. can be made to the invention by those skilled in the art 
Cooling water is circulated through the welding head by without departing from the spirit and scope of the inven- 
feeding water from input water line 9 into passageway 26 tlon as defined in the claims appended hereto. 
via suitable conduits (not shown), through passageway What is claimed is: 
26 to channel 30 and back up through passageway 28 to 1. An electric welding device that includes a welding 
water outlet line 8. head adapted to be positioned over a workpiece, said 
A metallic sleeve 38 is mounted within copper tube 24 10 welding head comprising: 
but is spaced therefrom so as to farm an annular passage- means for feeding a filler wire through the center of 
way 40 for feeding of inert gases to the weld area. Tube said welding head to the center of an area to be 
24 has a plurality of openings, as indicated at 42, which welded on the workpiece; 
permits gas to escape from chamber 40 into the weld a fixed electrode mounted in said welding head in a 
area. An inert gas such as helium is supplied to the in- 15 canted position relative to said filler wire, whereby 
terior of gas shield 5 via gas line 7 connected to passage- one end of said electrode is adjacent one end of said 
way 48 by suitable conduits (not shown) where it is dif- filler wire in a position immediately above the work- 
fused through openings 42. piece during a welding operation; 
A tubular guide sleeve 44 is mounted in tube 38 and is a cylindrical casing at one end of said welding head 
in close contact therewith. Sleeve 44 has a central open- 20 which surrounds the welding area and functions as 
ing therein through which a filler wire 45 from feed an inert gas shield; 
mechanism 4 can be fed into the weld area. Sleeve 44 is a conducting collar mounted to the interior surface of 
composed of an insulator material and functions to guide said casing; 
the filler rod to the weld puddle and to insulate the filler said fixed electrode being mo~~nted  in said collar in a 
rod from the remainder of the welding device. A copper 25 fixed and canted position relative to said filler wire; 
guide tip 46 is attached to the lower end of sleeve 44 a ring member attached to the inside surface of said 
and an annular fiberglass insulator 48 is attached to sleeve cylindrical casing for supporting said conducting 
44 just above the copper guide tip. collar, said ring member being composed of an in- 
Inert gas shield 5 has a ring member 49 attached to an sulator material and having a threaded interior sur- 
interior surface thereof in a position above the weld 30 face; and 
puddle area. Ring member 48 has a threaded portion 50 said conducting collar having a threaded exterior por- 
formed on the inwardly facing surface thereof for mount- tion that engages the threaded interior surface of said 
ing an annular conducting collar 52. Collar 52 is sup- ring member. 
ported by attachment to the lower end of tube 24 and 2. The welding device recited in claim 1 wherein said 
threadable engagement with ring 48. The conducting 35 welding head further includes: 
collar has a plurality of openings 54 formed therein that a tubular guide member of insulator material centrally 
permits the diffusion of gas to the immediate weld area. mounted in said welding head; and 
A tungsten electrode 56 is mounted in the conducting said tubular guide member having an opening extending 
collar in a fixed position, offset from center, and canted therethrough wherein said filler wire can be guided 
relative to the filler rod, the particular ~osi t ion of the elec- 40 through said welding head to the center of a weld 
trode offering many advantages as discussed above. area. 
The operation of the invention will now be discussed 3. The welding device recited in claim 2 wherein said 
with reference to FIGURES 4a-4d. As illustrated in FIG- welding head further includes circular diffusion holes in 
URE 4a, operation is initiated by admitting inert gas to said conducting collar through which inert gas can diffuse 
the weld area and applying a current to  electrode 56 via 45 and surround the weld area. 
copper tube 24 connected by suitable connections (not 
shown) to power line 8. Preheating of the workpiece References Cited 
occurs when the arc strikes the area of the workpiece, and UNITED STATES PATENTS 
a crater is formed in the workpiece, as illustrated in FIG- 2,868,$54 1,1959 skinner et ------- 219-130 
URE 4b. Filler wire is then fed into the crater as the tung- 50 2,868,956 1,1959 Lobosco --------- 219-130 
sten electrode melts the wire and the crater is filled. FIG- 2,892,925 6,1959 Butterfield et al. --- 219-130. URE 46 shows the crater partially filled. Cooling water is, 
of course, being circulated through the welding head dur- JOSEPH V. TRUHE, primary ~~~~i~~~ 
ing the operation. When the crater is filled, as illustrated 
in FIGURE 4c, the feed of filler rod is stopped and current 55 J- G. Assistant Examiner 
to the electrode is decreased. FIGURE-4d illustrates a 
solidified weld nugget. U.S. C1. X.R. 
It will be apparent from the foregoing description of a 219-75 
preferred exemplary embodiment of the invention that a 


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