FIELD OF THE INVENTION
The present invention generally relates to Gas Metal arc welding process. More
particularly, the present invention relates to a device for configurating and
feeding an uniformly bent wire with a preset pitch and amplitude to oscillate a
welding arc in narrow gap gas metal arc welding (GMAW) procedure.
BACKGROUND OF THE INVENTION
Narrow gap gas metal arc welding makes use of narrow grooves in the order of
12 mm. The welding arc has to operate inside the narrow groove and requires
that satisfactory fusion of the side walls without any significant defects is
ensured. For this purpose, single and double wire techniques are generally
adopted. In the single wire technique, the arc position is carefully manipulated to
ensure the required side wall fusion. The steps adopted are for example,
oscillation or rotation of the arc inside the narrow groove. To carry out such
steps, different mechanisms have been developed. The process makes use of
different types of wire bending devices to obtain a wire bent into a uniform
pattern so that the arc is oscillated in a controlled manner inside the narrow
groove. The available devices and the produced bent wires vary in their
complexity and design. Thus, providing a simple mechanism for feeding a
uniformly bent wire for oscillating the arc for narrow gap welding still has lot of
scope for improvement.
A wire bending system disclosed in the publication namely, BHK type Narrow Gap
GMA welding Process; Minoru KAWAHARA and Isao ASANO; Narrow Gap Welding
(NGW)-State of art in Japan 1986, Published by Japan Welding Society,
comprises a flapping device which has a tube guide for the wire that flapps from
one side to the other above a pair of wire feeding rolls. This arrangement
enables the wire to be bent into a sinusoidal wave form. But this system requires
a separate and additional flapping device to bend the wire.
US Patent no US4891493 discloses a gear type system in which the filler wire
passes through a pair of meshing sprockets. As the wire comes out of the
sprockets, the wire is bent into a zigzag fashion, the bent wire representing the
profile of tooth with sharp bends. To change the profile of the bent wire,
different set of sprokets with different profile have to be used.
OBJECTS OF THE INVENTION
It is therefore an object of invention to propose a device for configurating and
feeding a uniformly bent wire with a preset pitch and amplitude to oscillate an
arc in narrow gap gas metal arc welding (GMAW), which eliminates the
disadvantages of the prior art.
Another object of the present invention is to propose a device for configurating
and feeding a uniformly bent wire with a preset pitch and amplitude to oscillate
an arc in narrow gap gas metal arc welding (GMAW), in which a single drive is
used for bending and feeding of the wire.
An yet another object of the invention is to propose a device for configurating
and feeding a uniformly bent wire with a preset pitch and amplitude to oscillate
an arc in narrow gap gas metal arc welding (GMAW), which produces smooth
variable profile for the wire.
A further object of the invention is to propose a device for configurating and
feeding a uniformly bent wire with a preset pitch and amplitude to oscillate an
arc in narrow gap gas metal arc welding (GMAW), which eliminates the
requirement of any mechanical rotation of the wire or the wire-guide.
A still further object of the invention is to propose a device for configurating and
feeding a uniformly bent wire with a preset pitch and amplitude to oscillate an
arc in narrow gap gas metal arc welding (GMAW), which is capable of feeding
the wire with straight and bent profile without resetting of the system.
SUMMARY OF THE INVENTION
Accordingly, there is provided A device for configurating and feeding a uniformly
bent wire with a preset pitch and amplitude to oscillate an arc in narrow gap gas
metal arc welding procedure, the device comprising a wire spool (10)
accommodating a continuous wire; a wire-feeder (15) drawing the wire from the
wire-spool (10) via a wire-guide (14) for feeding the guided wire into a wire-
bending means (11,13), the wire-bending means is enabled to configure the fed
wire into a sinusoidal wave form so that the wire oscillates in a sinusoidal wave
form the arc after passing through the torch (17) at the tip of the wire inside the
narrow groove, and in that the bending means is enabled to vary the pitch and
amplitude of the wire by changing the preset parameters of the bending means.
The device is particularly adaptable for uniform bending and feeding of smaller
diameter wires into a uniform wave shape. The device has two spider wheels
each is coupled to a gear which mesh together during operation. One of the
spider wheels is mounted on a slide and is adjustable, thereby varying the center
distance of the spider wheels. The wire feed motor also drives the spider wheel
through a pair of meshing gears. The wire is bent into the required shape by a
plurality of free rotating grooved rolls provided on the spider wheels.
The device is capable of bending the wire smoothly into a sinusoidal wave form
without sharp bends by the grooved rolls during the rotation of the spider.
Various wires up to 1.6mm diameter can be used in this method.
The wave shape of the wire can be altered by varying the diameter of the freely
rotating rolls, adjusting the center distance between the spider wheels by
adjusting the slide position.
The device accommodates the wire bending and feeding means into a single
module. Any wire without any bending can also be fed by the same device. This
enables welding of the joint roots, which does not require any oscillation. The
smooth bending of the wire (wave form) enables the wire to be fed through the
long welding torch to the arc location without interruption or difficulty.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure-1 schematically shows edge preparation in a Narrow Gap Gas Metal Arc
welding procedure.
Figure-2 is a line diagram illustrating the principle of operation of the system
according to invention.
Figure-3 is a block diagram of a device according to the invention.
DETAILS DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
As shown in figure-1, a typical edge preparation technique employed for one side
Narrow gap gas metal arc welding comprises the steps of machining a joinable
component to have a J groove edge, assembling the two halves of the joints to
form a groove with an included single of (D) equaling 1 to 2°, the bottom of the
groove having a radius of 6 mm (C) thus making a joint of 12mm above the root,
the root thickness (B) variable between 3 to 5-mm depending upon the current
level employed, the thickness of joint (A) is variable upto 250 mm. Generally,
such edge preparation requires a backing plate (4) tack welded on the reverse
side to support the molten weld metal created by the welding arc.
As shown in figure-2, the principle of operation of the device according to
invention is that a wire (2) supplied in the form of a wire spool (1) is drawn by a
wire feeder (5) through a plurality of feed rolls (4). The wire (2) before entering
the wire feed rolls (4), passes through a wire bending means (3). The wire (2) is
bent uniformly by a rotating spider arms which carry the freely rotating rolls (4).
The uniformly bent wire (6) passes through a nozzle (7) before oscillating the arc
in a groove (8) formed by a base metal (9).
As shown in figure-3, the device basically is enabled to configure a metal wire in
a sinusoidal wave form to a preset pitch and amplitude. The device according to
the invention comprises a wire spool (10) on which a wire is stored. A wire
feeder (15) drawing the wire from the wire spool (10) for initially passing
through a wire guide (14) and feeding into a wire-bending means (11,13). The
wire bending means is disposed above the wire feeder (115), and comprises two
rotatable spider wheels (13) having a plurality of grooved rolls (11). The spider
wheels (13) in combination with the grooved rolls (11) configure the wire to a
sinusoidal wave form. The bent wire thereafter passes through a torch (17). The
wire feeder (15) being operated via an electric motor (15).
The operational method of the device according to the invention is as under.
A wire from a wire spool (10) is drawn by the wire feeder (15) located below a
wire bending means (11,13). The wire from the spool (10) passes through the
wire guide (14) and into the wire bending means. The wire bending means
(11,13) comprises two rotating spider wheels (13) having a plurality of freely
rotating grooved rolls (11). The wire is held in position by the grooved rolls (11).
The rolls (11), and the spider wheels (13) carrying the rolls mesh like a pair of
gears in rotation. The wire passing through the rolls (11) is smoothly bent into a
sinusoidal wave shape. The bent wire is drawn further, by the wire feed roll (15)
driven by an electric motor (16). The wire bent into the sinusoidal waveform is
marginally straightened when it passes through the wire feeder (15) but retains
the uniformity and passes on to the torch (17). The wire after coming out of the
torch (17) oscillates the arc at the tip of the wire inside the narrow groove.
WE CLAIM
1. A device for configurating and feeding a uniformly bent wire with a preset
pitch and amplitude to oscillate an arc in narrow gap gas metal arc welding
procedure, the device comprising:-
- a wire spool (10) accommodating a continuous wire;
- a wire-feeder (15) drawing the wire from the wire-spool (10) via a wire-guide
(14) for feeding the guided wire into a wire-bending means (11,13),
characterized in that the wire-bending means is enabled to configure the fed
wire into a sinusoidal wave form so that the wire oscillates in a sinusoidal
wave form the arc after passing through the torch (17) at the tip of the wire
inside the narrow groove, and in that the bending means is enabled to vary
the pitch and amplitude of the wire by changing the preset parameters of the
bending means.
2. The device as claimed in claim 1, wherein the wire bending means (11,13)
comprises atleast two rotating spider wheels (13) provided with a plurality of
freely rotating grooved rolls (11).
3. The device as claimed in claim 1, wherein the wire feeder (15) is driven by an
electric motor (16).
4. The device as claimed in claim 1, wherein the wire feeder (15) is disposed
below the wire bending means (11,13).
5. A device for configurating and feeding a uniformly bent wire with a preset
pitch and amplitude to oscillate an arc in narrow gap gas metal arc welding
procedure as substantially described and illustrated herein with reference to
the accompanying drawings.

A device for configurating and feeding a uniformly bent wire with a preset pitch
and amplitude to oscillate an arc in narrow gap gas metal arc welding procedure,
the device comprising a wire spool (10) accommodating a continuous wire; a
wire-feeder (15) drawing the wire from the wire-spool (10) via a wire-guide (14)
for feeding the guided wire into a wire-bending means (11,13), the wire-bending
means is enabled to configure the fed wire into a sinusoidal wave form so that
the wire oscillates in a sinusoidal wave form the arc after passing through the
torch (17) at the tip of the wire inside the narrow groove, and in that the
bending means is enabled to vary the pitch and amplitude of the wire by
changing the preset parameters of the bending means.