Note: Descriptions are shown in the official language in which they were submitted.
9~n
The invention relates to a welding yun, preferably an
arc weldiny gun in which a torch head having the welding
torch is placed in rotary driven manner at the front end of
a tubular protective casing.
Such welding guns are more particularly used for pipe
welding or welding pipes to a pipe plate, 60 that the torch
head must be rotatable about the pipe axis.
In certain weldiny processes, the torch head requires a
welding filler wire taken from a storage reel mounted at the
rear end of the welding gun in a reel holder connected in
non-rotary manner to the torch head, so that the reel is
rotated about its own axis and about the rotation axis of the
torch head. The welding filler wire is drawn from -the reel by
means of a driven pair of feed rollers and is fed through a
feed tube to the torch on the torch head. Such welding guns
must be as light and easy to operate as possible. It is
therefore inter alia desirable to be able to rapidly and
easily replace the filler wire storage reel.
To ohtain an optimum convenient construction of the
welding gun, the latter mus-t also have a minimum size in
such a way that it is very compact. Thus, the welding gun
can be manipulated very easily manually or on a manipulator.
A known welding gun has ! in addition to the gun handle, through
which in
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generally are introduced the electrical control
and supply lines, as well as inert gas and cooling
water lines, a separate casing for the rotary
drive of the torch head positioned in the vicinity
of the front part o the said head and which is
fitted to the tubular protective casing thereof.
The rotary axis of the rotary drive constructed
as an electric motor is perpendicular to the
rotation axis of the ~orch head and the reduction
gear connected between the rotary drive and the
said head is an angular toothed gear. Furthermore,
the reel holder for the filler wire reel located
in the rear part of the welding gwn is coupled
via a relatively long bearing shaft to the torch
head. Thus, in this known construction, the compact-
ness and convenience leave much to be desired.
In addition, the welding head can become
blocked in welding guns of this type in which the
rotary torch head is generally held in centred
manner in the pipe to be welded ~y means of a
rotary centring ~andrel. This can either lead to
damage to the toothed reduction gear, particularly
if it is not made particularly strong in order to
achieve an optimum compact~ space-saving construction
and/or the electri&al rotary drive of the rotary
torch head can overheat.
To achieve a good welding quality when
welding with a filler wire, it is also necessary
; to feed the said wire with a precise feed speed to
the torch on the torch head. The welding filler wire
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is generally fed to the torch head by means of
a pair of eed rollers comprising a driving roller
driven by means of a drive motor having a knurled
portion on its circumferential surface and a rotatably
mounted grooved roller cooperating with the knurled
portion of the driving roller and in whose circum-
ferential groove is laterally guided the welding
filler wire taken from the wire reel and travelling
through the gap between the pair of feed rollers.
The filler wire passing between the gap of the
pair of fe~d rollers is pressed by means of the
grooved roller against the knurled portion of the
driving roller, so that the knurled ribs are embedded
to a certain extent in the wire and advance the
latter in form-locked manner in accordance with the
rotation of the driven driving roller. As a function
of the inner wire material hardness, a relatively
high pressure is required for pressing the wire
against the driving roller. Therefore, the driving
roller must be correspondingly well supported, so
that it is not deflected by the contact pressure.
However, if ~he pair of feed rollers and the drive
motor driving the driving roller are made as small
as possible to reduce the amount of space for housing
them in the welding gun, a good support for the
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driving roller i5 ~ ~tained in the known guns, so
that it is necessary to work with a relatively low
contact pressure between driving roller and the
grooved roller of the filler wire feed roller pair.
One object o~ the invention is to provide a
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welding gun with a rotary torch head, which is
as compact and convenient as possible and can
be operated with optimum easeO
Another object of the invention is to
S provide a welding g~m with a rotary torch head
and an unwinding roller receiving the storage
reel for the filler wire, which by means of a
single operation can effortlessly and rapidly
be placed in and removed from the reel holder at
the rear end of the welding gun in a direction at
right angles to the reel axis.
Another object of the invention is to
provide a welding gun with a rotary torch head
in which the rotary drive thereof is positioned
at the rear end of its tubular protective casing
to ensure an optimum compact and convenient
construction of the welding gun and drives the
torch head by means of the reel holder supporting
the filler wire storage reel7
Another object of the invention is to
provide a welding gun with a rotary torch head
in which, in the case of a compact, convenient
construction, there is no risk of damage to the
torch head driving connection, even if the latter
is blocked.
Another object of the invention is to
provide a welding gun with a rotary torch head
and a filler wire storage reel from which the
wire can be removed by means of a pair of feed
rollers and is fed to the torch on the torch head
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which, with minimum compact dimensions, permits
the setting of a high contact pressure between
the filler wire and the driving roller of the
feed roller pair.
The invention is described in greater detail
hereinafter relative to non-limitative embodiments
and the attached drawings, wherein show:
Fig 1 a front view from the rear of a welding gun
constructed according to the invention.0 Fig 2 the longitudinal section through the rear
part of the welding gun of Fig 1 in side view.
Fig 3 the cross-section along the intersection line
of Fig 2.
Fig 4 the side view of the reel holder of Fig 2 in
plan view.
Figs 2 and ~ merely show the rear end of
the rotary welding head 2, which is completely
received in a protective tube 70 extended by a
rear protective tube 54 housing the welding gun
reel holder 4. The tubular protective casing of
the welding gun Eormed by protective tubes`54 and
70 is supported on handle 87 (Fig 1) by means of a
casing 71 r~mning along the bottom of the protective
casing and said handle introduces the supply lines
for the rotary torch head into the gun. Operating
switches 85, 86 as well as a plug socket 84 (Figs
1 and 2) are positioned on a side wall of the box-
like casing behind handle 37. Member 84 provides an
additional reference output for the electrical
control line of the welding gun to which can be
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connected e.g. corresponding indicating devices.
As can be gathered from Fig 2, in the rear
end portion of the box-like casing 71 is provided
the rotary drive 59 for torch head 2 in the form
of an electric motor with rearwardly directed motor
axis running parallel to the rotation axis of torch
head 2. A small chain wheel 74 is positioned on the
output shaft of rotary drive 59 and is coupled via
a drive chain 73 with a large driven chain wheel 75,
mounted in rotary manner on a shaft journal 76
constructed at the rear end of a reel holder 4
for receiving a filler wire storage reel 1 flanged
to the rear end portion of torch head 2. At the
rear, the shaft journal 76 passes into a journal
pin mounted in rotary manner in a ball bearing 79
having a smaller diameter than the shaft journal
and supported in the rear front cover 56 of the
tubular protective casing 54, 70. The driven chain
wheel 75 is located between two disk-like friction
rings 82 positioned on the shaft journal 76. One
friction ring is supported on a front shoulder
at the end of reel holder 4 and the other is supported
on a pressure ring 89, which is in turn resiliently
supported via cup springs 81 on a nut 83 screwed
onto the re~r end of shaft ~ournal 76 and secured
by means of a grub screw 88 on journal 76. Thus, a
slip clutch 77 is formed between the driven chain
wheel 75 and shaft journal 76 and consequently torch
head 2. The coupling force can be adjusted by corres-
ponding screwing adjustment of nut 83. Under the
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spring tension of cup springs 81, pressure ring
89 mounted in rotary and displaceable manner on
journal 76 is pressed against the following friction
ring 82, which transfers the contact pressure via
the driven chain wheel 75 to the other friction
ring 82 and consequently to the axial shoulder of
reel holder 4, so that the driving torque is
transferred by frictional resistance from the
driven chain wheel to the reel holder and therefore
to torch head 2 flanged to the front end of reel
holder 4 via flange 24.
As can be gathered from Fig 2, reel holder
4 is constructed as a four-sided, closed rectangular
frame3 whose frame side walls 33 bounding its
longitudinal sides are parallel to the rotation
axis of the torch head and reel holder 4. Figs
2 and 4 best show the mounting of the wire storage
reel 1 and the quick-change device which is provided
in preferred manner for the reel.
Perpendicular to the plane of the rectangular
frame formed by reel holder 4, a bearing slot 34
is ~ormed in each of the frame side walls 3,
approximately at the centre o~ the length thereof
~or mounting the unwinding roller 30 whose axis is
perpendicular to the rotation axis of the torch
head and holder 4~ The bearing slots 34 are open
towards one lateral edge of the frame side walls33.
At the other end thereof, the slot base 38 is curved
in semicircular manner complementary tothe circum-
ference of the associated bolt ends 37 of bearing bolt
--8--35, 36 of unwinding roller 30. The bearing bolt
comprises two bolt portions 35, 36 which axially
bisect it in each case inserted from one front
- side of the unwinding roller 30 into the hollow
boss 31 thereof until a peripheral shoulder 44
formed on the bolt portions 35, 36 engages on the
associated front disk 32 fixed to the particular
end of said boss 31. Thus, the unwinding roller
30 with the filler wire storage reel 1 can be
inserted in the bearing slots of the frame side
walls 33 perpendicular to the plane of the frame
formed by holder 4, so that bolt ends 37 meet the
slot base 38 and the particular outside of shoulder
44 of bearing bolt 37, 36 engages on the inner
surface of the associated frame side walls 33.
Thus, the unwinding roller is mounted in axially
fixed manner in the reel holderg~
For locking the unwinding roller 30 to
bolt ends 37 of bearing bolt 35, 36 a locking fork
40 is provided, whose plate-like fork members 41
have a reciprocal spacing corresponding to the
spacing of the outside of khe frame side walls 33.
At the free ends of the two fork members 41, the
locking fork 40 is pivotably articulated to the
frame side walls 33 in an extension of the longitudinal
axes of bearing slots 34 and at a distance from slot
base 38. A locking projection 42 is ~ormed on the
edge of the fork members 41 facing the bearing slots
34 and in the locking position of the locking fork
40 said projection overlaps the associated bol~ end
2 ~
37 of bolt 35, 36 of roller 30 resting on slot base 38 and
therefore locks the bolt in the associated bearing slot 34.
The fork web connecting the fork members 41 at -the rear end
of reel holder 4 forms an actuatiny web 43 arranged in the
locking position of the locking fork at a distance from the
edges of frame side walls 33 having the open end of beariny
slot 34. A swivel bolt 46 is swivellably mounted in a slot
in the rear frame transverse wall 45 of reel holder 4 which
swivellably passes through an opening in the centre of
actuating web 43 of lockiny fork 40 and facing the latter.
To this end, the passage opening 62 for swivel bolt 46 is
conically countersunk from both sides of actuating web 43, so
that a knife edge bearing-like ring rib is formed approximately
in the centre of opening 62 on which bolt 46 swivellably engages.
Swivel bolt 46 carries a spring 39 t whose one end is supported
on bolt 46 and whose other end is supported on the bottom of
actuating web 43. To ensure that under the tension of spring
39 web 43 does not slide from the free end of bolt 46, the
latter has on its end projecting over web 43 a cross pin 61,
which simultaneously defines the locking position of locking
fork 41~ Thus, under the tension of spring 39, locking form
41 is held in its locking position, so that during its rotation
about the rotation axis of torch head 2, perpendicular to the
reel axis and reel holder 4 on bolt ends 37 unwinding roller
30 is held in bearing slots 34.
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To remove the unwinding roller 30 from
the reel holder 4, it is merely necessary to
depress actuating web 43 counter to the tension
- of spring 39, so that the locking projections of
fork members 41 of locking fork 40 release the
bolt ends 37 of unwinding roller 30 a~d the latter
can be moved from reel holder 4. To enable this
to take place, without disassembly of protective
tube 54 large windows 60 are formed on the two
diametrically facing longitudinal sides of
protective tube 54. One end of the window is
provided over the feed roller pair 6, 8 or
filler wire 3 and the other end over actuating
web 43 of locking fork 40.
As can be gathered from the drawings, the
edge 47 of fork member 41 on the back of locking
projections 42 remote from slot base 38 in the
locking position of locking for~ 40 projects
over one lateral edge of bearing slot 34 at an
obtuse angle to the longitudinal direction of the
slot. On inserting a new unwinding roller 30 in
reel holder 4, bolt end 37 of bearing bolt 35, 36
~ runs on the edges 47 of fork members 41 and press
: back the locking fork counter to the tension of
spring 39~ without any separate actuation o~ the
fork 40 on actuating web 43 being necessary. As
soon as bolt ends 37 meet the slot base 38 of
bearing~slot 34, locking fork 40 automatically
returns to its locking position.
Thus, the unwinding roller 30 is rotatably
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held in reel holder 4. Its rotary movement is
driven by removing the filler wire 3 by means o:E
the driven feed rollers 6, 8. To ensure that there
is no free lagging of roller 30, a brake plunger 48
is displaceable counter to the tension of a spring
52 in one frame side wall 33 and under the tension
ofspring 52 it engages with its friction head 53
on one front disk 34 of unwinding roller eccen-trically
to the reel axis. Brake plunger 48 is displaceable
in a bearing bush 49 fixed to frame side wall 33
and its rear end 50 projects beyond the outer edge
of bearing bush 49. A cross pin 51 is there placed
through the brake plunger 48 and under the tension
of spring 52 is supported on the outer edge of
bearing bush 49. Front slot pairs 53a of different
depths and reciprocally displaced by 90 are formed
in this edge of bearing bush 49. Depending on
the front slot 53a in which cross pin 51 of brake
plunger 48 is located the br ~ g force acting
between friction head 53 and front disk 32 of
unwinding roller 30 on the latter is larger or
smaller, so that it is easily possible to adjust
the braking force by Gorresponding rotation of brake
plunger 48. To remove the unwinding roller 30, brake
plunger~48 is rotated by less than 90 at its
cross pin Sl, so that the latter is supported on
the slot-free part of the edge of bearing bush 49
and consequently friction head 53 of brake plunger
48 is raised from the associated front disk 32 of
roller 30 and consequently the latter is disengaged
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from brake pl~mger 48.
The wire feed for the filler wire is
housed in the front frame cross wall 78 o reel
holder 4 flanged to torch head 2 via flange 24,
as is shown in Figs 2 and 3. The filler wire 3
removed rom the storage reel 1 is introduced
by means of a wire insertion tube 2 into the roller
gap between a pair of feed rollers comprising a
driving roller 6 and a grooved roller 8 and from
the said gap is supplied by a wire feed tube
23 to the not shown torch part of torch head 2.
Guiding roller 6 is positioned in overhung manner
on output shaft 9 of the reduction gear of a drive
motor 5 constructed as an electric motor housed in
the reel holder 4 by means of a pressure plate 25
perpendicular to the rotation axis of the torch
head. On the circumference of driving roller 6
there is a knurled portion 7 with which is linked
a support ring 10 formed on roller 6, so that ring
10 is arranged between knurlecl portion 7 and drive
motor 5. On support ring 1OJ clrive roller 6 is
supported by a support roller 11 formed by the outer
ring o~ a ball bearing mounted on either side ~
reel holder 4 by means of a bearing bolt 12. Support
roller 11 faces grooved roller 8 diametrically
with respect to the driving roller 6, so that the
spindles of rollers 11, 6 and 8 are in a common
plane which is perpendicular to the rotation axis
of torch head 2. However~ rollers 6, 8 and 11 are
displaced rslative to the rotation axie oi torch
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head 2.
On either side, grooved roller 8 is mounted
in an adjusting rocking arm 13 mounted in reel
holder 4 by its spindle 14 parallel to the spindles
of rollers 6, 8 and 11 and spaced from the plane
containing the axes of the latter. At its free end,
it has a blind hole 15, which is perpendicular
to rocking arm spindle 14 and parallel to the plane
containing the spindles of the three rollers 8, 6
and 11 on their side remote from spindle 14. One
end of a helical spring 16 i5 supported o~ the
bottom 20 of blind hole 15. Its other end i3 supported
on head 21 of a thrust bolt 18 ~ projecting
into helical spring 16. The head 21 of thrust bolt
18 has a diameter corresponding to that of blind
hole 15, so that it can pass into the latter. At the
front end of head 21 of thrust bolt 18, an adjusting
screw 17 in the extension of the axis of helical
; spring 16 and thrust bolt 18 is screwed into reel
holder 4.
Thus, as a function of the setting of screw
; 17, it is possible to adjust the contact pressure
with which the grooved roller 8 presses wire 3
against driving roller 6. This adjustment of the
contact pressure takes place initially by corresponding
~: tensioning of helical spring 16. However~ on adjusting
screw 17 to such an extent that end 19 of thrust bolt
18 strikes the boktom 20 of blind hole 15, spring 16
is eliminated and then screw 17 via bolt 18 engages
directly on the adjusting rocking arm 13 to further
increase the contact pressure.
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