Note: Descriptions are shown in the official language in which they were submitted.
- 1~22281
This is a division of Canadian patent application
Serial No. 311,418 filed September 15-, 1978 entitled Stud
Welding Tool.
The present invention relates to welding apparatus
which is particularly suited to welding studs to a panel,
and more particularly to a stud welding tool which allows
the operator to weld studs in locations which are generally
inaccessible to prior art devices of this type.
One of the more common methods of attaching
elements to a metal panel surface is through the use of
studs which are welded to the surface providing either a
threaded or T-shaped male fastening element protruding from
the surface. These studs are generally applied by stud
welding devices of the hand-held type. Typical of these
devices are the units disclosed in U.S. Patents 3,645,419
issued February 29, 1972 to N. Shorrock, 3,546,420 issued
December 8, 1970 to D. H. Ettinger et al, and 3,597,572
issued August 3, 1971 to D. H. Ettinger et al, all assigned
to the assignee of the present invention.
The prior art stud welding guns referred to above
have proven to be adequate for most operations wherein stud
welding is employed, and this type of device has generally
proven to be commercially successful. However, many
applications are confronted where the stud is required to
be applied normal to a surface having a limited access area
above the surface due to related structure. Particularly
in the area of automobile construction where trim is to be
provided around the curved portions of relatively small
window openings, the panel surface onto w~ich the stud is
to be welded is relatively inaccessible to a stud welding
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1~222~3~
gun of the type found in the prior art, and commercially
available. There are, therefore, many areas on an automotive
body as well as in other constructions, which lend themselves
to stud welding application, but have never been susceptible
to such practice because of tool interference in the weld
area.
The present invention, therefore, has an object
to provide a stud welding device which is capable of attach-
ing studs to a work surface which area has heretofore been
inaccessible to stud welding devices of the prior aYt.
A further object of the invention is to provide a
stud welding device which is as simple in construction and
lightweight, while achieving the aforementioned objective.
As will be observed in the more common prior art
stud welding guns (such as those referred to in the above-
cited patents), the design provides that substantially all
of the motions facilitating a stud weld operation are
located on the centerline of the stud or stud collet. The
location of the various elements employed to produce the
motion during a stud welding operation are also therefore
located on the centerline and cause interference when the
gun is employed to apply a stud to a work surface having
restricted area above the surface.
The presend invention, therefore, provides the
mechanics necessary to produce those motions facilitating
a stud weld operation in an area offset from the stud or
collet holder, and generally the motion producing elements
extend at substantially right angles to the centerline of
the stud.
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According to a broad aspect of the present
invention there is provided a device for arc welding
headed studs to a work surface wherein the studs are fed
seratim to a stud retaining collet. A receiver block having
a first cylindrical bore formed therein through which a stud
is fed axially in a downward direction to the collet is also
provided. A second bore is formed in the block and has an
internal cross-section substantially T-shaped to accommodate
a headed stud fed therethrough in a direction normal to the
stud axis. The second bore is directed downwardly t~
intersect with the first bore to form an angle in the range
of 0.5 degree to 5 degrees.
For a clear understanding of the invention,
reference should be made to the following description of
the preferred embodiments taken in onjunction with the
accompanying drawing, wherein:
FIGURE 1 is a bottom perspective view showing a
preferred embodiment of the invention,
FIGURE 2 is a side elevation view, partially in
~ection showing details of the structure of Fig. l;
FIGURE 3 is a side elevational view partially in
section similar to Fig. 2 but showing details of the
structure at one stage during the operation of the device;
FIGURE 4. is a side elevational view, partially
in section, similar to Figs. 2 and 3, and showing details
of the structure during another stage in the operational
sequence of the device;
figure 5 is a side elevational fragmentary view
of an alternate preferred embodiment of the invention
showing details of the structure,
~:12Z2~31
FIGURE 6 is a side elevational fragmentary view
similar to Fig. 5 showing details of the structure at one
stage during operation of the device;
FIGURF 7 is an elevational sectional view taken
along the line VII-VII of Fig. 6 showing further details
of the invention,
FIGURE 8 is an elevational sectional view taken
along the line VIII-VIII of Fig. 6 sho~ing additional
detail of the invention:
FIGURE 9 is an elevational sectional view 'aken a
along the lines IX-IX of Fig. 6,
FIGURE 10 is an elevational sectional view
showiny details of a portion of the device shown in Figs.
5 through 9, taken on an enlarged scale for clarity,
FIGURE 11 is a top plan view showing the structure
of Fig. 10~ and
FIGURE 12 is an elevational sectional view similar
to Fig. 10 showing a modification to the structure of Figs.
10 through 11.
Referring now to the drawings, and in particular
to Figures 1 through 4, there is shown an arc welding device
embodying the invention and comprising a main body 10 having
a pair of coextending frame members 11 and 12. The body 10
further comprises a top plate 13 connecting the frame members
11 and 12, and in the embodiment shown the members 11 and 12
and the plate 13 are formed from a single sheet of metallic
material.
A pair of fasteners 14 and 15 serve to attach an
angle bracket 16 to the top of the plate 13 and an electri-
cally operated solenoid 17 to the bottom of the plate 13.
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A pistol grip type handle 18 is attached to the upwardly
extending flange of the angle bracket 16 and extends above
the main body 10 of the welding device. The handle 18 may
be fabricated from a plastic or other suitable material
and is provided with a trigger 19 connected to a switch
(not shown) located within the handle.
The trigger 19 is spring biased outwardly from
the handle and when depressed by the index finger of the
user, closes the contacts in the switch which is connected
to a pair of lead wires 20 and 21. The switch may ~e of any
type well-known in the art which has contacts suitable to
complete the circuit on pressing the trigger 19 and to
break the circuit when the trigger 19 is returned to its
position as shown in Figures 1 and 2.
Returning to the frame members 11 and 12, it will
be noted that the rear of each member is connected by a pin
22 extending through each member and through the end of a
lever arm 23 which is disposed midway between the frame
members and coextensive therewith. A pair of insulator
bushings 24 and 25 serve to maintain the lever arm in
spaced relation with the frame members.
At the opposite end of the lever arm 23 from the
pin 22 is a receiving block 26 having a circular bore 27
formed therein substantially at right angles to the lever
arm. A stud gripping collet 28 is received in the bore
and retained in place by virtue of a set screw 29 threadedly
received through the wall of the portion of the block 26
forming the bore 27.
The lower end of the collet 28 comprises a
plurality of spring-like fingers which receive and grip a
1122~81
stud S as shown in Figures 1 through 4. The upper portion
of the collet 28 is provided with internal threads for
receiving an adjustment screw 30 and lock nut 31 in combi-
nation. The adjustment screw 30 may be moved into, or out
of, the collet 28 to limit the length of that portion of
the stud S extending from the collet, as various lengths
of studs are employed in the device.
At the forward end of the main body 10, a
substantially U-shaped member 32 is connected to the forward
end of the frame members 11 and 12. The U-shaped connecting
member 32 has its lower portion formed around the collet
28 to provide a flash shield 33 in closely spaced relation
with the collet.
Each of the frame members 11 and 12 is provided
with an inwardly turned flange 34 and 35, respectively,
which contain a threaded bore. A pair of adjustment screws
36 and 37 are received in the flanges 34 and 35 and a pair
of lock nuts 38 and 39 retain the screws in the set posi-
tion.
The angle bracket 16 is provided at either side
with a pair of tabs 40 and 41 which extend forwardly and
above the flanges 34 and 35 respectively. Each of the tabs
40 and 41 has mounted on the underside thereof a tubular
member 42 and 43, respectively, which are manufactured of
an insulating material. A pair of coil springs 44 and 45
are received within the tubular members 42 and 43.
As best shown in Fig. 2, the lever arm 23 has a
cross member 46 which extends to either side of the lever
arm and is located between the tubular members 42 and 43
and the flanges 34 and 35. At either side of the cross
~f~
arm 46 there is mounted a stud 47 or 48, formed of
insulating material and extending through the cross arm
46. Each of the studs 47 or 48 has its head portion below
the cross arm to act as a stop for the adjustment screws
36 and 37, and its shank portion extending upwardly from
the cross arm to receive the coii springs 4~ or ~5.
By virtue of this arrangement, the lever arm 23
is biased downwardly by the coil springs 44 and 45 to a
position where the adjustment screws 36 and 37 contact the
insulated studs 47 and ~8.
Approxlmately midway between the collet 28 and
the pivot pin 22 the movable cylinder of the solenoid 17
i5 attached to the lever arm 23 by a pin 49. ~ power line
50 is also ~nnected to the lever arm 23 and serves to
transmit a welding current to the lever arm during operation
of the device.
A pair of wires 51 and 52 connect the solenoid
17 into a control circuit which is not shown for purposes
of simplicity.
In prac~ice, the circuit into which the lead
wires 20 and 21, the solenoid wires 51 and 52 and the
power line 50 are connected may be constructed in accord-
ance with teachings which are well known in the stud
welding art and will therefore not be explained in detail
here, as it is not a part of the present invention. For
instance, the circuit disclosed in U.S. Patent 3,582,602
issued June 1, 1971 to D. ~. Ettinger et al, may be
modified slightly to provide power to the solenoid 17 and
the power line 50 through operation of the trigger 19, to
produce the desired operation of the elements described
above, as will be explained in detail in the description
of the operation of the device.
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~lZZ2~31
The operation of the device is best explained by
referring to Figures 2, 3 and 4. In Figure 2, a stud S is
to be attached to the work surface W by means of the stud
welding technique. The stud S is inserted in the collet
28 and the adjusting screw 30 is turned such that the stud
extends slightly below the flash shield 33. As the stud S
is placed against the work surface W, downward pressure on
the handle 18 causes the lever arm 23 to pivot about the
pin 22 compressing the springs 44 and 45 until the flash
shield touches the work surface W as shown in Figure 3.
The adjustment screws 36 and 37 have been so located that
there is stlll space between the cross arm 46 and the
tubular members 42 and 43.
It will be noted that the pivoting of the lever
arm 23 displaces the pin 49 and as a result displaces the
armature of the solenoid into the solenoid body. However,
as noted before, it does not displace all of the gap which
has been adjusted and provided in the tool set-up.
As shown in Figure 4, when the trigger 19 is
manually squeezed it is effective to close the switch (not
shown) enclosed in the handle 18, closing the circuit
connected to the lead wires 20 and 21. The circuit is
arranged such that the power line 50 is energized and the
solenoid 17 is also energized through the wires 50 and 52.
Energization of the solenoid causes the lever arm 23 to be
lifted, pivoting about the pin 22, and the stud to be
lifted or displaced away from the work surface W.
As the stud S is lifted from the work surface W,
an electric arc flows from the work surface W to the stud
S. The heat of the arc which melts the work surface W and
the stud S produces a molten metallic surface at the end
of the stud and a pool of molten material at the work
surface. After a predetermined time lapse which may be
measured in miliseconds, the circuit is broken and the
solenoid 17 is turned off from its power source causing
the springs 44 ~nd 45 to force the lever arm 23 downward
about the pivot point at the pin 22. By virtue of the
downward movement of the arm 23, the molten end of the
stud S is plunged into the melt pool of the work surface
W for the completion of the stud weld.
Referring now to Figures 5 through 8, there is
shown an alternate embodiment
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l~Z22B~
of the subject invention having an automatic stud feeding feature embodied into
a similar structure to that described with reference to Figures I through 4.
The embodiment of Figures 5 through 8 comprises a decorative housing
53 forming a hand grip for the user, and containing the various working elements
of the welding device.
Within the housing 53 there is located a main body 54 comprising a pair
of frame members 55 and 56 which are retained between the walls of the housing
53. In addition to the frame members 55 and 56, the main body 54 of the welding
device comprises a top plate 57 to which is attached an electrical solenoid 58.
The solenoid 58 is attached to the plate 57 by a fastener 59 at the rear, and a
fastener 60 at the forward end of the solenoid serves to fasten the solenoid anda bracket 81 to the plate.
At the rear of the main body 54, a pin 62 is fixed between the frame
memb\ers 55 and 56. A lever arm 63 comprising arm members 64 and 65 is attached
to the main body 54 by the pin 62 and is retained in spaced relation from the
frame members 55 and 56 by a pair of insulated spacers 66 and 67. l'he arm members
64 and 65 extend forwardly from the pin 62 and are attached to a receiving block
68 located at the forward end of the welding device. The receiving block 68
is provided with a circular bore 69 which i8 suitably threaded to receive a stud
holding collet 70.
As in the previous embodiment, each of the arm members 6g and 65 terminate
in a U-shaped configuration forming a flash shield 71, which is best shown in
Figures 5 and 6. Also, as in the previous embodiment, substantially midway
between the pin 62 about which the lever arm 63 pivots, and the collet 70, the
arm members 64 and 65 are attached to the movable portion of the so]enoid 58
by a pin 72, as best shown in Figure 8.
Referring to Figure 9, it will be noted that in addition to the arm members
64 and 65, a pair of links 73 and 74 are pivotably attached to the pin 62 at their
one end, and have their opposite end pivotably attached to a stud feed arm 75
compriSing side members 76 and 77. The side members 76 and 77 extend forwardly
_ 9 _
1~222~1
to a point above the flash shield 71, where they are received in a slotted cylindrical
boss 78, and retained by a pin 79.
The slotted boss 78 is connected to a stud feed rod 80 which extends
downwardly into the circular bore 69. The stud feed rod 80 is of a diameter
slighly smaller than the bore 69 to provide a sliding fit in the bore, while the
boss 78 is larger than the bore and has a shoulder portion which contacts the
block 68 to limit the extension of the rod into the collet 70 to a point adjacent
the end of the collet, as shown in Figure 5.
Referring now to Figure 5 taken in conjunction with Figure 7, it will
be noted that about midway between the connecting point of the so]enoid 58 to
the lever arm 63, and the receiving block 68, the arm members 64 and 65 extend
upwardly and form a saddle plate 81 on which is mounted a double acting air
cylinder 82. The cylinder 82 has a piston rod 83 which projects downwardly
between the side members 76 and 77 of the stud feed arm 75 and is pivotably
secured to the stud feed arm by a connecting pin 84.
Referring to Figure 7, it will be seen that the lever arm 63 is spring
biased towards the work surface in similar fashion to the embodiments shown
in Figures 1 through 4. As shown here, the frame members 55 and 56 are provided
with a pair of lower flanges 85 and 87, respectively, into which adjustment screws
87 and 88 are threadedl~y received. The upper portion of each of the frame members
55 and 56 are provided with a pair of upper flanges 89 and 90, respectively,
each having a tubular member 91 and 92 mounted on the underside thereof.
As in the previously described embodiment, the lever arm 63 is provided with
a pair of insulated studs 93 and 94 having a portion extending upwardly to receive
a pair of coil springs 95 and 96, which are in turn received in the tubular members
91 and 92. The lower portion of the studs 93 and 94 further serve to act as stops
for the adjustment screws 87 and 88.
As best shown in Figures 5 and 6, a flexible air line 97 is attached to
a suitable source oi air pressure and connected to the cylinder 82 and electrical
connections are made to the solenoid 58 and the lever arm 63 similar to that in
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112Z2~
I the prior embodiment. A trigger 98 serves to operate a switch located in the
housing 53 which is connected to a circuit arrangement effective to sequence
the operation of the device, as will be described hereinafter. The various elements
of the circuit need not be explained in detail as a number of such arrangements
could be used with the invention to acheive the desired results and these elements
per se are not part of the present invention.
Referring now to Figures 10 through 12, there is shown an automatic
stud feed arrangement in which a stud feed line 99 is connected to the receiving
block 68. The stud feed line 99 is generally of flexible material and has an internal
bore 100 which is T-shaped to àccommodate headed studs as they are fed therethrough
in a direction normal to their stud axes. The stud feed line 99 may be connectedto the receiving block 68 by any suitab]e means which will provide a quick disconnect
of the device from the feed tube. As shown, the T-shaped internal bore 100
of the feed tube 99 matches a similar T-shaped bore 101 provided in the receiving
block 68. The T-shaped bore 101 in the receiver block 68 intersects the circularbore 69 into which the headed stud is fed axially to the collet 70. Spring action
of the collet 70 is effective to hold the stud in place, the stud head diameter being
slightly larger than the internal diameter of the collet.
It will be noted that the T-shaped bore 101 in the receiving block 68
intersects the circular bore 69 at a slight downward angle.
It has been found that by introducing this downward angle in the intersection
of the bore 69 with the T-shaped bore 101, studs which are fed by air pressure
through the feed line 99 have less of a tendency to jam in the intersection of
the two bores and are better aligned to receive the stroke from the stud feed
rod 80 due to the slight angle introduced into the feed path. Generally, it is
found that an angle of from one half to five degrees is sufficient to introduce
the stud into the circular bore 69 such that the amount of jamming occuring in
the device is minimized.
In Figure 10, the stud feed line 99 extends upwardly and enters the
ZZZ~l
receiving block 68 at an upward angle, while in Figure 12,
an alternative arrangement is shown wherein the stud feed
line is substantially at right angles to the circular bore
69. However, in either instance, the downward angle of
the intersection of the T-shaped bore 101 with the circu-
lar bore 69 in the received block is maintained to create
an improved feed path, which has been found to produce
less jamming in the feed operation.
Referring now to Figures 5 and 6, in operation
the device is similarly attached to a control circuit as
the device previously described in respect to Figures 1
through 4. However, in addition the double-acting cylin-
der 82 is attached to a suitable source of compressed air
through the air line 97, and the stud feed line 99 is
attached to a supply of headed studs, which are arranged
to be fed by compressed air to the receiving block 68,
through the stud feed line. The feeding of the studs as
well as the operation of the double-acting air cylinder
82 may be accomplished through any convenient circuit
arrangement. The circuit arrangement also may be a modi-
fication of that shown in U.S. Patent 3,582,602 which
modification is within the capabilities of one skilled in
the art, to achieve the operation which will be herein-
after described.
In the initial position shown in Figure 5, the
welding of a stud S to the work surface W has been accom-
plished and the device is about to be removed from the
work surface extracting the stud S from the collet 70.
When the device is removed from the welded stud S, a
signal is forwarded to the control circuit either manually,
or by automatic means such as the breaking of the ground
between the device and the work surface W, and a ready
state is initiated in the circuit. At this point the
cylinder 82 is activated and retracts causing the piston
rod 83 to lift the side members 76 and 77 resulting in
the stud feed rod being retracted to the position shown
in Figure 6. In sequence with this operation, a stud is
fed through the stud feed line 99 by compressed air and
into the receiving block 68 coming to rest at the inter-
section of the T-shaped bore 101 in the block, and the
circular bore 69. The double-acting cylinder 82 is then
activated to reverse the piston rod 83 and the stud feed
rod 80 is plunged into the position shown
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L~
~:12228~
in Figure 5 forcing the stud S into engagement with the end portion of the collet
70 .
The air pressure is maintained on the cylinder 82 and the device is now
operated in a manner substantially as described with reference to the device
shown in Figures 1 through 4.
The stud S is introduced to the surface W as shown in Figure 5 and a
slight pressure is applied to the device until the flash shield 71 touches the work
surface W. This causes the lever arm 63 to be moved upwardly and displaces
the solenoid armature mechanically into the solenoid body, as in the previous
embodiment. The trigger 98 is then depressed causing the lever arm 63 to be
energized and the solenoid 58 lifts the stud and displaces it from the work surface
W to produce the arc, after which the springs 95 and 96 force the lever arm 63
downwardly and the stud S is plunger into the pool of molten metal to become
permanently attached to the work surface W.
From the description above, it should be appreciated that even with
the modifications of Figures 5 through 12 the device remains simple in operation,
and provides a tool which allows the stud applying portion thereof to be introduced
into heretofore unaccessible areas, for the application of headed studs.
