An bngmttnmg Welding Investigation of

An bngmttnmg Welding Investigation of
An
Investigation of Electric Welding
electrical
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X
UNIVERSITY OF ILLINOIS
LIBRARY
Class
Book
Volume
AN INVESTIGATION OF ELECTRIC WELDING
BY
ANDREW MELVIN DUNLAP
ARTHUR HIRAM MUNCH
THESIS
FOR THE
DEGREE OF BACHELOR OF SCIENCE
IN
ELECTRICAL ENGINEERING
COLLEGE OF ENGINEERING
UNIVERSITY OF ILLINOIS
19
11
UNIVERSITY OF ILLINOIS
May 29
THIS
IS
TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BY
Andrew TJelvin Dunlap
entitled
IS
190L1
and
Arthur Hiram Munch
An Investigation o£ Electric Welding
APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE
degree OF
Bachelor ofLBoienoe in Sleet rioal Engineering
Instructor in
Charge
APPROVED:
HEAD OF DEPARTMENT OF Electrical Engineering.
197591
.
TABLE OF COITTEIITS.
page
Introduction
History of Electric Welding
1
Methods of Welding
1
a.
Resistance
b. Arc
Lie t hod
2
Lie t hod
4
Figure Uumher I
5
Use of Electric Welding in Manufacturing
6
Advantages of Electric Welding
8
TESTS.
Description of Apparatus Used
12
Figure Number II
Method of Making Welds
14
Testing of the Welds
15
Methods of Computing Results
3-
6
RESULTS
18-27
Tables Humber I to I inclusive
28
Curves
Plate 1
29
Plate
2
30
Plate 3
51
Plate 4
•
32
Plate
5
23
Plate
6
34
Conclusions
55-37
Digitized by the Internet Archive
in
2013
http://archive.org/details/investigationofeOOdunl
O
.
IiTTHODUCTIOU
The following pages contain the results of an investiga-
tion of the methods of electric welding, including a short history
of the invention and perfecting of the process.
A description of
some of the machines used in the practical application of the process to present day manufacturing, and actual tests made by the
writers of this thesis on a number of small specimens.
The machine used was designed to weld small specimens
by the resistance method.
Herein is also shown the data obtained
from the tests, together with the results obtained from the series
of readings as well as from the results in general obtained at
various times from other experiments, and from the actual use of
the process by manufacturers in their shops.
HISTORY OP ELECTRIC WELDING.
Since the discovery of the electric current many important
and useful inventions have been made, which utilize this wonderful
agent in the production and manufacture of various commodities.
The adaptability of this same agent to the welding of
metals, was, however, absolutely unknown to the world until Prof.
Elihu Thompson obtained patents dated Aug. 10, 1886, which may be
regarded as the foundation of the new art.
The earlier use of the process was but little more than
an experiment, yet it showed as a result that the new method was
entirely practicable and efficient both as to cost and strength of
weld.
Previous to the discovery of this method iron and steel
were almost the only metals that could be welded, but the writer
of an article on electric welding in the Engineering Hews of May 5,
1888 states that the process has been used successfully on all
kinds of metals and their alloys, butween metals of like kinds, and
between those of a different structure and composition, as steel and
copper, or lead and brass.
The process has been growing in favor from year to year,
and
nev/
ways for its use in the manufacturing Indus tires are con-
stantly being discovered.
Its cleanliness, rapidity, economy,
efficiency and ease of control has
recommended it wherever its use
is possible.
METHODS OP WBLBIMS.
The methods by which the results are obtained are per-
fectly simple and are two in number, namely, the resistance method
and the arc method.
RESISTANCE IJETHOD.
It has long heen known that the electric current has a
heating effect upon a conductor when passed thru it, the amount of
heating depending upon, the resistance the conductor offers to the
flow of current and the amount of current flowing.
The amount of
this resistance depending upon the size, length and material of
the conductor.
The relation of the heating effect to the resistance
of the conductor and the current in the conductor is given by the
expression,
Heating
Where
I
R
= I
is the strength of the current in amperes and R the value
of the resistance in ohms.
The amount of heat is measured in Bt.U.
or more roughly by the rise in temperature.
equation we see that
I
From the preceeding
must vary inversely with R, that is, v/hen
welding material having a small resistance the value of
I
must be
increased.
Iron having a comparatively low resistance will require
a correspondingly larger current to produce a
\.
elding heat.
The
resistance of a conductor decreases with increase of cross-section,
so more current must he used for large stock than for smaller stock
of the same material and vice-versa.
The resistance of the stock
alone does not produce a welding heat but the reduced area in
actual contact between the pieces to be welded, together with the
impurities at that point, such as rust, scale, dirt etc. increases
the resistance very materially, so much so, in fact that this
increased resistance is the main factor in localizing the heat,
one of the most important advantages of the process.
.
3.
The current used in the resistance method may be obtained
direct from a direct current generator, or from an alternating
current generator, afterwards passing it thru a step-dowr
transformer
In the first case the current is generated at the desired
voltage and used directly on the welding machine.
In the second
case it is generated at a high voltage and low current then changed
in the transformer to the desired voltage and current value.
The
second arrangement is usually the more practicable and convenient
since the power for welding may be used at greater distances from
the generator.
The first method requires a heavy copper conductor
to carry the large current, which prohibits the welding operation
from being carried on at any great distance from the direct current generator.
The welding transformer in the simplest form
consists of a soft iron core around which is wound the primary
winding consisting of many turns of small insulated wire, over this
is would a few turns of heavy insulated copper cable which compose
the secondary coil.
The terminals of this secondary coil are then
firmly attached to clamps which hold the pieces tc be welded.
The
generator current may have a potential, from 110 volts up to the
high pressures of the power circuits 2300 volts and higher.
voltage is transformed or converted, according
bo
This
the ratio of
transformation to enormous current values sometimes as high as
40000 amperes, as in the case of rail welding, the pressure however
being very low, from
2 to 4
volts.
The pieces to be welded are clamped solidly in the
special terminals of the secondary coil, the surfaces to be welded
are then brought together and held with a high pressure while
4.
welding, the switch is closed and a few seconds suffice to produce
a perfect weld.
The amount of current is exactly regulated by a
resistance in the primary circuit or in some instances in the field
of the generator where the whole power output of the generator is
used in the welding.
Cn passing the current thru the pieces to be welded the
heat at the point of contact rises rapidly until condition of
fusion is reached in "both pieces, at which point the current is
turned off, the metal running together and forming a perfect union.
The heating is uniform since if any certain part "becomes hotter
than the remainder that part has a greater resistance than the
cooler portion and so receives less current and therefore less
beat until the temperature "becomes uniform over the whole area.
ARC IISTKOD.
The second method of welding
"by
means of the electric
current mates use of the electric arc, which has a temperature of
an ertremely high value ranging from 5000 to 4000 degrees centigrade.
There are several different methods in arc welding, the
two most important being the Zerener and Bernardos methods.
The
Zerener or "blow pipe method makes use of the arc maintained
"between two carbons, being directed against the metals to be welded
by the action of an electromagnet.
The apparatus employed is much
like direct current flaming arc lamps the carbons approaching
each other at an angle.
The electromagnet produces an effect upon
the arc similar to that of a blow torch the arc flame being directed
away from the carbon points in a concentrated pencil like form and
having a high temperature.
The work to be welded is so placed
.
5.
that the arc may
"be
directed against it.
The general construction
of the apparatus is such that it is useful within only a narrow
range, such as small castings and other small work of a rougher
nature
In the Bernardos arc welding process the work to be
welded forms one terminal of the direct current circuit and a carWith the switch closed the carbon is
bon electrode the other.
touched to the work and then drawn a short distance away until an
arc is formed between the terminals.
This arc
'has
such a high
temperature that metals may be entirely melted away, cut in two,
or fused into one piece.
The circuit for control of the current
which ranges from 400 to 1000 amperes must be so arranged as to
give a variable resistance and one method is as shown in the
following diagram.
Circuit Breaker
A 711 meter
Vo/fStefer
Carbon
water bt>l.
\
Steel
Materials
d
i
B/ocks^
*-St<?ef
Figure 1.
Diagram Showing ilethod of Current Control, in the
Bernardos Arc '/elding Process.
VS
To£/rte
.
Girds may
"be
used in place of the water resistances, lugs being
provided at different points for the attachment of the wires in
order that the resistance in the circuit may be varied.
The car-
bon varies in size according to the size of the work to be done
and is from one half to two inches in diameter.
The heat and light
given off by this process is so intense that the operator must be
thoroughly protected leaving no part of the body exposed as an
inflamation similar to a sunburn may be produced.
entirely done by hand requires a skilled operator.
The work being
This arc is
used for removing extra metal, for cutting thru bars, for filling
in and for building on metal to castings.
destruction of the Ferris
at 3t
.
./heel on the
It wa3 employed in the
grounds of the V/orld's Fair
Louis
USE OF ELECTRIC 7/ELDIUG
III
MANUFACTURING.
As has previously been stated, the simplicity of the
process makes its use possible in an ever increasing number of
industries.
Its chief use at present is found in the welding of
small machine parts, the manufacturing of wire fencing, the making
of shells and tubing, and the bonding and welding of the rails of
city and interurban railways.
Carriage and buggy axles, and tires
of all sizes are electrically welded, the only limit to the size
of material being the value of current that may be produced, how-
ever practical use of the process has not been attempted on stock
over
2
in.
in diameter or on rectangular pieces over 4 sq. inches
in sectional area.
A very useful application of the process is in
repairing broken machine parts which otherwise would require a
new piece.
Bta.cn
use has been found for it in the manufacture of
automobiles and bicycles, while several large plants use it in the
.
7.
production of steel tubing of all sizes up to sixteen inches in
7ith the increased use of the process there has
diameter.
wonderful development of welding machines.
operated
"by
"been a
The simplest type is
hand and consists of two clamps which receive the
current and hold the material with a lever or screw for producing
the pressure.
Welding machines are now built that operate auto-
matically and continue in operation so long as power and material
is supplied.
Chain welding and wire fence welding machines are
excellent illustrations of automatic machines.
It has been found
that automatic machines will produce more perfect welds than the
most skillful hand operators wherever they can be used.
There are three types of welds that are made by this
process, the butt weld, the lap weld, and the spot weld.
In making
a butt weld a burr or fin is produced which must be removed.
The
lap weld is familiar to all and can be produced in a perfect form.
The spot weld is peculiar in that only a small part of the sur-
faces in contact are welded.
This weld is used in joining sheets
or plates of steel or iron of less than one quarter inch each in
thickness
In operation the electrodes or secondary terminals are
placed opposite each other with the metal plates between them,
pressure is applied and the current turned on.
In a few seconds
the sheets are welded in a spot as large as the electrodes.
By
welding several points in this manner the sheets are firmly
fastened togehter.
?or the welding of rails special apparatus of a heavy
and costly nature is necessary.
The outfit consists of three cars,
one containing a booster set, one a rotary converter, and one a
:
8.
welding transformer.
The transformer is swung from a heavy "beam
projecting in front of the car and so mounted as to allow it to be
moved from side to side and raised or lowered at will.
The sec-
ondary circuit of the transformer constitute the jaws of the clamp
and are made hollow to provide for water cooling.
ADVANTAGES OP ELECTRIC WELDI1TC.
The chief advantages of the process of welding metals
"by
the use of the electric current may be briefly enumerated as
follows
1.
It is simple in operation, requiring little skill on
the part of the operator, hence eliminating the expense of skilled
labor.
2.
The operation is almost instantaneous, thus the work
of welding may be carried on successfully with great rapidity.
3.
The operator has perfect control over the process
and can vary the current, pressure and time of operation to suit
the work in hand.
4.
Correct alignment of the parts welded is assured
since the machine clamps rigidly hold the parts in the desired
position, during the operation.
5.
The weld is made in full view of the operator, en-
abling him to closely observe each part of the process.
6.
In making the weld, the interior of the joint receives
the heat before the exterior, hence there is greater possibility
for a perfect weld than with the process of heating the metal in a
coal or gas fire where the exterior is the first part heated.
7.
The heat is localized at the weld, no other parts
being effected, therefore little danger of injuring the composition
.
9.
or destroying the finish on parts adjacent to the weld itself.
8.
The process is free from danger of any kind of shock
to the operator, for alt ho a very large amount of current is
necessary to produce the welding heat, the potential which forces
it
thru the joint is very low.
9
.
The pressure applied
"by
the operator during the pro-
cess forces the slag and scale out of the weld, driving out many
of the impurities from the metal.
10.
The economy of
tills
method compared with others is
clearly evident since all the energy applied is utilized in pro-
ducing the weld, none is wasted when the welding is not in process.
11.
This method has made possible successful welding of
such metals as copper, "brass, aluminum which heretofore have
difficult to weld
12.
"by
"been
other processes.
There is a distinct absence of noise, dirt, smoke,
intense heat, and dangerous gases, so often present when welding
metals by other processes.
DESCRIPTION 0? APPARATUS USED.
All the welds made in this investigation were made by
the resistance method upon a simple machine designed and constructed
by James William Shaw as part of a thesis on Methods of Welding
Metals, for the degree of Bachelor of Science at the University of
Illinois
The machine consists of two cast iron jaws mounted upon
a lathe bed, the jaw A being in two parts, the upper part being a
heavy brass plate insulated by fiber board from the heavy cact
iron base which is clamped to the lathe bed.
The jaw B is in three parts, consisting of a heavy cast
10.
iron base clamped to the frame, this piece carries a sliding block
of cast iron, the two being dovetailed together, to this second
piece is attached the toggle joint connecting with the hand pressure
lever by means of which a heavy pressure is brought to bear upon
the specimens to be welded.
Upon this sliding piece but insulated
from it by fiber board is a second large brass plate.
To these
plates are secured the terminals of the secondary coil.
Groves
are cut into these plates to receive the specimens to be welded.
Clamps and bolts for holding the specimens are fixed in these cop-
per plates.
In setting the specimens in the jaws the possible
pressure may be regulated as desired by placing the specimens in
the jaws so that when they are in contact the toggle joint is in
more or less of a straight line.
The transformer was also designed and built by Mr. Shaw.
It is of the shell type, having 168 turns of number 14 double
cotton covered magnet wire for the primary coil, and three turns
of number 0000 insulated cable for the secondary coil, and is
immersed in transformer oil in a case to prevent overheating.
The core loss of the transformer with 110 volts and 60
cycles on the primary is 23.5 watts, magnetizing current .47
amperes.
Using 220 volts on the primary the core loss is 71.5
watts, and the magnetizing current .97 amperes.
The resistance of
the primary is .787 ohms.
The instruments used were, a Westinginghouse portable
integrating wattmeter calibrated to read in watt minutes.
This
instrument has two sets of voltage terminals, one for 110 and the
other for 220 volts.
it
A system of plugs in the current coil makes
possible to use values of current in the primary circuit up to
11.
40 amperes.
The ammeter was 01 the Thompson type with a range from
to 50 amperes.
range from
The voltmeter
to 300 volts.
v/as
a Weston instrument with a
The diagram of connections is self ex-
planatory, power entering at the double pole switch which connects
with the primary of the transformer.
12
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e oooooooo
-G
(2>
/yyure
Z
14.
METHOD OP ELKim WEEDS.
The resistanoe method was employed exclusively in welding
the specimens.
Bar iron was obtained and cut into test specimens,
six inches in length.
faced.
One end of each test piece was carefully
Two of these pieces were then clamped in line between the
jaws of the welding machine, with the faced ends about l/ Q of
an inch apart.
The switch controlling the flow of current in the
primary circuit was then closed and immediately following the
specimen pieces were forced together by means of the hand lever.
The latter action closed the secondary circuit of the transformer
and instantaneously a heavy current flowed thru the test pieces.
The pressure exerted on the specimens was increased or decreased
as desired, thereby increasing and decreasing the resistance be-
tween the pieces and causing a larger or smaller amount of current
to flow in the secondary circuit.
Y7hen the
metal had reached its fusion point, the primary
switch was opened and a slightly greater pressure exerted on the
specimen in order to force out any burnt metal, slag or scale
from the center of the weld.
63 specimens of mild steel in sizes ranging from 3/ 16"
to l/2 inch were welded.
machine steel of sizes
9
specimens each of wrought iron and
5/ 8 of an
respectively were also welded.
inch in diameter and 3/ 8" x 3/8"
The average voltage impressed on
the primary of the transformer ranged from about 110 and 220 volts
for the small stock to about £50 volts on the larger size specimens.
It was found that on account of the small size of the welding trans-
former, that 220 volts on the primary of the same was not sufficient
to give the necessary current to weld stock larger than 3/8 of an
.
15
inch in diameter, hence higher voltages had to
"be
.
resorted to.
Too large a value of current will "burn the metal "before
the operator can effect a weld while too small a value of current
does not "bring the metal up to its fusion point, hence it was found
only by experiment, the "best value of current for the size of
material to
"be
welded.
It is hoped however that the following data
given in pages 18 to £7 inclusive may
"be
of assistance in serving
as a rough guide in future work along this line
ITo
flux was used on welding any of the specimens and
judging from the results obtained in this test it is reasonable to
believe that the use of
fltix
would be of no special advantage in
this method of welding metal.
TESTIIIG-
OF THE WELDS.
After welding the specimens, the burr or swelled joint
at the weld was turned down to the original diameter of the stock
and each specimen tested for ultimate tensile strength, in order
to determine the efficiency of the weld.
This operation was per-
formed on a Riehle Testing Machine in the Laboratory of Applied
Mechanics at the University of Illinois.
The ends of the specimen
was securely clamped in jaws of the machine and load applied until
rupture occurred.
The welds which were perfectly annealed with-
stood the strain and the specimen ruptured at a distance from the
weld itself.
Other welds in which the metal was less perfectly
annealed, containing slag, scale, or burnt metal, broke in the
weld itself.
Samples of the stock, from which the welded specimens
were made, ?;ere also tested for ultimate tensile strength.
The
efficiency of the weld was then determined by the ratio of the
16.
ultimate tensile strength of the welded specimen to that of the
material itself, expressed in percent.
In a number of cases, the ultimate tensile strength of the
welded specimen was greater than that of the material, giving the
welds a percent efficiency greater than ICO.
It was noted that the cold rolled machine steel specimens
had a high elastic limit or yield point and that the cross-sectional
area of the welded portion was reduced about one-third of its or-
iginal size just before rupture occurred.
This does not refer to
the "necking down" of the specimen at point of rupture but to a
general elongation of the specimen between the machine jaws.
METHODS OF C01IPUTIIIG RESULTS.
The ultimate tensile strength of a specimen is the
highest stress that the specimen can sustain before rupturing, when
under tension.
The efficiency of a welded specimen or the weld is
the ratio of the ultimate strength of the specimen to that of the
material itself, expressed in percent.
referring to specimen
For example in Table 1,
it is seen that the ultimate tensile
2,
strength of the specimen is 1840 lb. and the ultimate tensile
strength of the material is 1900 lb.
the weld is
x 100%
=
Therefore the effeciency of
96.8$.
The value of secondary current was obtained by multiplying the value of primary current used by 56 since the ratio of
turns on the primary and secondary coils is 56
:
1.
The value of
magnetizing current was so small in comparison with the primary
current, that it was neglected.
In computing the power consumed in producing the welds,
the transformer losses were neglected on account of their small
.
17.
value in comparison to the power used.
power for each well it
v/as
In figuring the cost of
necessary to charge these losses up to
the weld.
The wattmeter used, recorded the power used for producing
each weld, in watt hours.
This was easily reduced to kilowatt
hours by dividing the value obtained from the instrument by 1000.
The cost of power was figured at three commercial rates,
two, four, and six cents per kilowatt hour, as shown in the tables
on pages 13 to 27.
Tables were made showing the results of welding each
size of stock.
These show for each specimen, time of welding,
average secondary current, average power in kilowatt hours, ultimate
tensile strength of each welded specimen and material from which it
was made, percent efficiency of weld, cost of producing the weld at
three rates of cost, and the primary voltage impressed on the
transformer
.
.
18.
Table I.
lild Steel
3/16 inch Diameter.
3E
Ho. of
9
Specimen
Time in
Seconds
15
Average
current in
Secondary
amperes
12
10
10
10
10
15
10
13
613.5 613.5 684.0 670.0 544.0 583.0 621.0 641.0 600.0
Power in
K. W. hours
.0049
.0038 .0037 .0036
.0029
.0031 .0051 .0034 .0043
Ultimate Tensile Strength
of Specimen
1920* 1840* 1910*
lbs
1590 1900*
1740 1950*
1400 1900*
Ultimate Tensile Strength
of Material
lbs.
1900
1900
1900
1900
1900
1900
1900
1900
1900
J^ff^ciency of
Weld in percent
100+
96.8
100+
73.2
100
91.6
100+
73.7
100
Cost of 7/eld
in Oerts at
2, 4, 6 cents
per U. V/. hr.
,0098
,0196
,0294
Primary
Voltage
Used volts
.0077 .0074 .0072 .0058 .0063 .0102 .0068 .0086
.0154 .0149 .0144 .0116 .0127 .0204 .0136 .0172
.0231 .0224 .0216 .0175 .0190 .0507 .0205 .0258
107.0 105.5 108.5 108. 5 107.0 109.5 110.0 108.5 111.0
The use of the asterisk indicates that the
specimen broke outside of the weld in testing for ultimate tensile
Strength of welds
SE. indicates that the specimen peices had beveled ends
before being welded.
*IIote.
.
19
Table II.
Hild Steel 1/4
incli
Diameter.
Ho. of
Specimen
Time in
Seconds
15
30
41.5
41.5
43.5
8
41.5
684
868
810
863
1390
756
Average
current in
Secondary-
Amperes
1550
1005
1310
.0107
.0085
2500
1500
1950
3080 3080* 3120* 3130*
3230
3230
3230
3230
3230
3230
77.4
46.4
60.3
95.4
95.4
96.6
Power in
K. W. hours
.0100 .0107 .0194 .0181 .0202 .0122 .0173
Ultimate Tensile Strength
of Specimen
lbs.
3630
3120
3230
3250
3230
96.9
100+
96.6
Ultimate Tensile Strength
of Material
lbs
Effeciency of
Meld, in per-
cent
Cost of TCeld
in Gents at
.0214 .0170 .0200 .0214 .0388 .0362 .0404 .0244 .0346
2, 4, 6, cents .0428 .0340 .0400 .0428 .0776 .0724 .0808 .0488 .0692
per K. 7. hr.
.0642 .0510 .0600 .0642 .1164 .1086 .1212 .0732 .1038
Primary
Voltage
Used Yolts
145.5 217.5 217.5 106.0 108.7 108.7 108.5 221.3 111.3
20
Table III.
Hiia Steel
Ho. of
Specimen
Time in
Seconds
Average
Current in
Secondary
Amperes
Power in
"57.
hours
K.
1/4 inch by
V4
inch.
12345 6789
BE
7
38
6
21.5
72
26.5
23
28
20.5
27.7 15.76 28.63 19.60 13.45 18.60 17.50 18.26 18.80
.0116 .0239 .0102 .0254 .0284 .0268 .0155 .0193 .0139
Ultimate Tensile Strength
of Specimen
lbs.
3510
3270
3790 3570*
3000 3630* 3600* 3570* 3950*
3840
3840
3840
3840
3840
3840
3840
3840
3840
91.7
85.2
98.8
93.0
78.1
94.5
93.8
93
100+
Ultimate Tensile Strength
of material
lbs.
Efficiency of
Veld in percent
Cost of TCeld
.0232 .0478 .0204 .0508 .0568 .0736 .0310 .0386 .0278
in Cents at
.0464
.0956 .0408 .1016 .1136 .1192 .0620 .0772 .0556
cents
2, 4, 6
.1434
.0612 .1524 .1704 .1604 .0830 .1158 .0834
.0696
per K. \7. hr.
Primary
Yoltage
Used Yolts
216
144
213 216.8 105.6 141.5 139.0 136.5
130
Pi
Table IV.
Mild Steel
ITo.
inch Diameter.
5/ 16
of
Specimen
1
2
3
Time in
Seconds
10
10
10
4
8.5
5
32.2
6
7
8
9
24
37
40
21
Average
Current in
Secondary
Amperes
25.30 28.15 28.25 28.15 19.40 29.15 19.60 18.60 23.65
Pov/er in
K. 17. hours
.0152 .0170 .0173 .0145 .0235 .0264 .0271 .0291 .0216
Ultimate Tensile Strength
of Specimen
Ids.
4.R70
4-7AO
^7^0
4000
4685
4685
4605KS
4685
4685
4685
4685
4685
4685
97.7
100 +
79.6
85.3
58.4
73.8
82.6
95.0
82.4
3870* 4450*
3060
Ultimate Tensile Strength
of Material
lbs.
JZ \J
Efficiency of
*.7eld
in per-
cent
Cost of 7/eld
in Cents at
.0304 .0340 .0346 .0290 .0470 .0528 .0540 .0582 .0432
2, 4, 6 cents .0608 .0680 .0692 .0580 .0930 .1056 .1084 .1164 .0864
per K. 77. hr. .0912 .1020 .1038 .0870 .1410 .1584 .1626 .1746 .1296
Primary
Voltage
Used Yolts
217 218.5
220
218 136.5 135.7
135 140.9
157
22.
Table Y.
Wrought Iron
Ho. of
Specimen
z/ 3"
Diameter.
1234567
89
BE
Tine in
Seconds
25.5
19
17.5
20
16.5
16
21
17
16
Average
Current in
Secondary
Amperes
1547
1784
1995
1670
1605
1905
1625
1653
1778
Power in
K. W. hours
.0582 .0557 .0586 .0415 .0319 .0321 .0367 .0298 .0354
Ultimate Tensile Strength
of Specimen
5900
5360
3480
3800
4975
3980
3900
3650
4370
lbs.
5070
5070
5070
5070
5070
5070
5070
5070
5070
Efficiency of
Weld in percent
76.8
66.3
68.6
74.8
98.1
78.5
77.8
70.0
86.3
Ids.
Ultimate Tensile Strength
of Material
Cost of Weld
.0764 .0704 .0772 .0815 .0638 .0642 .0734 .0596 .0668
in Cents at
2, 4, 6 cents .1528 .1428 .1544 .1660 .1276 .1284 .1468 .1192 .1336
per K. w. nr. .2292 .2142 .1716 .2490 .1914 .1926 .2202 .1788 .2004
Primary
Yoltage
Used Yolts
211 215.3
217
215.5 209.5
212 217.5
214
237
23.
Table VI.
Machine Steel
3/8" by 3/8" (Gold Rolled)
BE
Ho. of
Specimen
1
2
Tine in
Seconds
15
18
22
21
17
19.5
22.5
24
20
2117
2106
1893
1980
2023
1953
1875
1905
1932
.0378
.0413
,0430
.0445
6250
6680
8370
6930
Average
Current in
Secondary
Amperes
Power in
V/. hours
K.
4
5
6
8
.0372 .0442 .0506 .0490 .0420
Ultimate Tensile Strength
of Specimen
lbs.
8960
7370
6220 10310 10100
Ultimate Tensile Strength
of Material
lbs
.
14425 14425 14425 14425 14425 14425 14425 14425 14425
Efficiency of
77eld in per-
cent
43.3
58.0
48.0
62.1
51.1
43.1
71.5
70.1
Cost of TCeld
in Gents at
.0756 .0826 .0860 .0890 .0744 .0884 .1012 .0980 .0840
2, 4, 6 cents .1512 .1652 .1720 .1780 .1488 .1768 .2024 .1960 .1260
per K. ¥. hr. .2268 .2478 .2580 .2670 .2252 .2652 .3036 .2940 .2520
Primary
Voltage
Used Volts
240 219.8
213 214.2 214.3
254
240
216
219
24
Table VII.
Mild Steel
Mo. of
Specimen
Time in
Seconds
Average
Current in
Secondary
Amperes
Power in
,7.
hours
K.
7/l6 n Diameter.
123456789
BE
BE
25
25
35
23
23
25
21.5
£3.5
20.5
1932
1950
1905
1867
1948
1952
2000
1950
1867
.0495 .0496 .0670 .0427 .0478
.0600 .0513 .0546 .0448
Ultimate Tensile Strength
of Specimen
lbs.
7340
8730 9030*
7840
8690
8720
8580
7900
9010
9225
9225
9225
9225
9225
9225
9225
9225
9225
79.6
94.7
97.8
85.0
94.3
94.6
93.1
85.7
97.7
Ultimate Tensile Strength
of Material
lbs.
Efficiency of
Weld in percent
Cost of Weld
in Gents at
.0990 .0992 .1340 .0894 .0956 .1200 .1026 .1092 .0896
Cents
.1980 .1984 .2680 .1708 .1912 .2400 .2052 .2184 .1792
2, 4, 6
per E. jjf. hr. .2970 .2976 .4020 .2562 .2868 .3600 .3078 .3276 .2688
Primary
Yoltage
Used Volts
206.7
205 202.4 204.0 215.7 240.0 240.0 240.0 240.0
25
Table Till.
Llild
Steel
7/16" by 7/16"
BO. of
Specimen
12
Tine in
Seconds
30
56
36
25.5
229S
2033
2261
2560
Average
Current in
Secondary
Amperes
Power in
£. W. hours
3
4
BE
BE
6
7
8
9
35.5
29
28
28
30
2170
2275
2178
2232
2198
5
.0861 .0907 .1068 .0780 .0990 .0875 .0803 .0827 .0884
Ultimate Tensile Strength
of Specimen
lbs.
10460 10150 13220
9800 11240 12400 10860 11500 10880
Ultimate Tensile Strength
of Material
lbs.
13255 13255 13255 13255 13255 13255 13255 13255 13255
Efficiency of
'Jeld in percent
70.9
76.6
99.9
73.9
84.9
95.6
01.9
86.8
82.1
Cost of vveld
in Cents at
.1722 .1814 .2136 .1560 .1980 .1750 .1606 .1654 .1768
cents
.3444
.3628 .4272 .3120 .3960 .3500 .3212 .5308 .3556
6
2, 4,
per X. './. hr. .5166 .5442 .6408 .4680 .5940 .5250 .4018 .4962 .5504
l*rimary
Voltage
Used Volts
252 247.8 265.8 261.6 259.8 267.0 265.3 267.6 270.0
26.
Table IX.
Uild Steel
V 2"
Diamet
BE
BE
Specimen
1
2
3
4
5
6
7
8
9
Time in
Seconds
25
33
45
18
27
30
28
26
29
2660
2352
2328
2703
2473
2315
2024
2182
2370
ITo.
of
Average
Current in
Secondary
Amperes
Pov;er in
K. TC. hours
.0843 .0950
.1220 .0688 .0875
.0918 .0776 .0754 .0885
Ultimate Tensile Strength
of Specimen
lbs.
6330 9720* 9610*
9800 9750* 9730* 9690* 9800* 13070*
9890
9890
9890
9890
9890
9890
9890
9890
9890
63.0
98.3
97.2
99.1
98.6
98.4
97.8
99.1
100+
Ultimate Tensile Strength
of Material
lbs.
Efficiency of
\7eld in per-
cent
Cost of 77eld
in Gents at
.1686 .1900 .2440 .1376 .1750 .1836 .1552 .1508 .1760
2, 4, 6 Gents .3372 .3800 .4880 .2752 .3500 .3672 .2328 .3016 .3540
per K. w. nr. .5058 .5700 .7320 .4128 .5250 .5508 .4656 .4520 .5310
Primary
Voltage
Used Volts
255 246.6 236.6 285.0 264.0 267.6 276.0 267.0 260.0
.
.
.
.
27
Table X.
Data from which curves are plotted
Kind of Gross- Average Average Average
UltiSpecimen section second- Power
area in ary cur- in K.W. mate
Strength
se, in. rent am- hours
of Specperes
imen in
.
.
Average Cost of Power
at
Effi4>e
ciency
6/j
2/2
in per- per per per
cent
1Z
•
hr
V/
•
.
X
•
T7 •
hr
.
"K
•
V/
hr
lbs
::iid
Steel
is"
di«meter
sy
.0058
1770
92.8
.007
.015
.022
1115.6
,0194
3545
92.1
.042 .079
.115
.0492
1026.2
.0141
2790
85.0
.028
.056 .084
,0768
1599.8
.0202
3958
83.9
.042
.085
.127
.1105
1724.4
.0553
5955
77.5
.068 .142
.205
.1405
1976.0
.0435
7910
55.0
.075
.259
.1520
1950.1
.0519
8427
91.4
.104 .207 .311
.1912
2222.7
.0999
11168
84.5
.178 .555
.533
.1965
2578.5
.0879
9722
94.6
.175
.527
.0276
618.8
.0625
Llild
Steel
l/4" by
V 4"
Mild
Steel
1/4"
diameter
::iid
Steel
5/
16"
diameter
V/r ought
Iron
3/8"
diameter
Llachine
Steel
5/8" by
5/8"
.168
Steel
7/
16"
diameter
Llild
Steel
7/
7/
16" by
16 r
Mild
Steel
diameter
.542
.
28
CURVES
The curves as shown on Plates 1 to
6
inclusive are de-
signed to show the relation "between size of specimen and the
following; current input, power consumed, cost of producing the
weld, average ultimate tensile strength, efficiency of the weld
and percent of specimens of each size stock which ruptured in the
weld when tested for ultimate tensile strength.
Plate 1 shows a curve, giving an idea of the amount of
current actually used in welding the different sizes of specimens
Plate
2
gives a curve showing the variation cf power
consumed in making welds with different sizes of stock.
The curves on Plates 3 and 4 are designed to shov; the
average percent efficiencies obtained from the welds of different
sizes of specimens.
The curves of ultimate tensile strength of
material and welded specimens on Plate 3 give an idea of the rang
of the percent efficiencies plotted on Plate 4.
The graphs of relative cost of welding different sizes
of stocl: on Plate
5
are worked out for power costing two, four,
and six cents per kilowatt hour.
The curve on Plate
6
is
designed to show the percent
of the number of specimens of each size stock which when tested
for ultimate tensile strength ruptured outside of the weld proper
U.
OF
I.
S. S.
FORM
50.
U.
OF
I.
6. S.
FOAM
3
31.
U.
OF
I
S. S.
FORM
31
32.
U.
Or
I.
S. S.
FORM
»
34.
U.
OF
I.
S. £.
TOHM
3
.
35.
C0HCLUSI01IS
From these tests on welding of metals
method it nay
"by
the resistance
seen that the proper values of voltage, current
"be
and time for obtaining satisfactory welds of different sizes of
material cannot
"be
definitely given.
The value of voltage used
on the primary side of the welding transformer ranged from 102 to
Corresponding voltage values on the secondary side of
285 volts.
the transformer were 1.8 to 5.1 volts respectively.
The lowest
value of secondary current used for welding was 613.5 amperes,
used on
3/ 16
inch stool:, the highest "being 2660 amperes, which was
used to weld stock
1/ 2
inch in diameter.
The curve on Plate 1
shows the average values of current used to weld the other sizes
of specimens.
The average time required in performing the operation
varied from 11 seconds on the smallest size specimens to 30 second
for the larger sizes.
It was found that by using a low value of
voltage and of current much longer time was required to secure
a desirable weld.
Tiien
high voltage is available,
use it in preference to low voltage.
it
is better to
In the case of using a step
down transformer in connection with the welding machine, as was
used in this test, high voltage in the primary causes a correspond
ing high current to flow in the secondary circuit of which the
test specimens form a part.
Using a high value of current, as is
consistent with the size of tne parts to be v/elded, for a short
time, is to be preferred to a lower value of current for a longer
time, since in the first case, the metal is quickly brought to a
welding heat and slight pressure is required to effect a good
union of the metals, and force out slag, scale, burnt iron, etc.
•
36.
from the center of the welded portion.
The total nizmber of specimens welded was 81.
Of these,
65 were of mild steel and 9 each of wrought iron and machine steel.
11 percent of the total number of welded specimens were found to
have a weld efficiency of over 100 percent.
56 percent had an ef-
ficiency of over 95 percent, and 4S percent possessed an efficiency
greater than 90 percent.
16 percent of the total number gave a
percent efficiency less than 70.
One third of the welded specimens,
when tested for tensile strength broke outside the weld proper.
Difficulty was experienced in obtaining good welds from
the cold rolled machine steel.
As may be seen by the efficiency
curve on Plate 4, the average efficiency for the nine specimens
welded, was only bb%.
It was noted in the test for tensile strength
that this material is highly elastic, possessing a high yield point.
Examination of the ruptured specimens brought out the fact that the
metal was not well fused to form a perfect union at the weld.
Some difficulty was also experienced in Yielding of wrought
iron.
As shown in the Table 5 on page 22
,
the best results were
obtained in a specimen welded from test pieces having beveled ends.
TJith one exception,
this specimen,
(Ho. G), required less power
than the others and gave a high efficiency of 98.1 percent.
This
clearly shows the advantages of beveling the ends of pieces to be
welded.
Glancing over the tables from page
it is seen that in the majority of cases,
to page
inclusive,
specimens having beveled
ends consumed a comparatively small amout of power when welded and
gave high percent efficiencies. The reason for this is probably
that when welding pieces having beveled ends, the welding process
starts at the center and as the pressure is increased, the weld was
37.
made from the center outwards.
This action tends to force the
slag, scale, and other impurities out
o±"
the center of the weld.
The "best results were obtained in making welds from the
l/s inch stock of mild steel.
.
Of the nine welds made from this
size stock, eight gave efficiencies of over 97 percent.
The aver-
age amount of power used in producing these welds was less than
that used in welding 7/16 inch by 7/16 inch stock of the same kind
of material.
It will be noted that a relatively high value of
primary voltage was impressed on the welding transformer when
welding this size material.
A general examination of all the ruptured specimens
brought out the following points:
In every case where the metal at the weld was properly
fused, the specimen ruptured at some distance from the weld.
In other cases where the specimen ruptured at the weld,
evidences were found of the presence of burnt metal, slag, scale,
and other impurities.
Other specimens showed the cross-sectional area of the
welded portion considerably reduced, indicating that that portion
altho not perfectly welded withstood a heavy strain before rupturing
As mentioned in "Methods of Testing Welds", the burr or
swelled portion around each weld was turned down to the area of the
stock before being tested for tensile strength.
This action evi-
dently reduced the efficiency of the weld to some extent.
V
jag
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